The best answers to these questions that I've seen are in the book Expected Returns, which I reviewed here.
For buy-and-hold strategies: leverage (borrowing to invest) can be used to increase returns. The Sharpe ratio of a portfolio is a measure of it's risk/reward trade-off; there's a theorem that given a set of assets with fixed known distributions and ability to borrow at the risk-free rate, the Kelly optimal allocation is a leveraged version of the portfolio with highest Sharpe ratio. You can calculate that optimal leverage in various ways.
In practice, we don't know future Sharpe ratios (only the past), we don't have assets with fixed known distributions (to the extent there is a distribution, it likely changes over time), and there's other idiosyncratic risks to leverage.
Using past data, however, is highly suggestive that at least some leverage is a great idea. For instance, a 40/60 stock/bond portfolio has higher Sharpe ratio than a 100% stock portfolio in almost all historical models since bonds and stocks have low correlation. It's not unreasonable to assume that low correlation will hold going forward. If I leverage up a stock/bond portfolio to the same volatility as the corresponding 100% stock portfolio, I see a 2-4% increase in yearly returns depending on time period. This is easily achievable by buying leveraged ETFs.
Naive Kelly models will usually recommend more risk than the stock market, so if your risk tolerance is even higher the (potentially naive and misleading) math is on your side. Be careful if you might need the money soon: these models assume you're never withdrawing!
My opinion: ~1.5-2.5x leverage on stock/bond portfolios looks reasonable for long-term investors, although it really depends on the assets -- short term treasuries for example are so stable that even 10x leveraging isn't crazy.
In the real world, you can leverage by:
You can kind of backtest various strategies for yourself using e.g.:
Keep in mind that the past doesn't predict the future, and naive back-testing might not track historical reality perfectly or may be missing some idiosyncratic risks of leveraging certain ways.
For your maximal laziness, here's an ~1.9x leveraged ETF allocation I made up just now that's around 40/60 world stock market/long-term bonds: 36% TMF, 16% SSO, 8% VXF, 40% VXUS. Full disclosure: Lots of people would think this is a terrible allocation since "everyone knows" the bond market is due to crash due to current low interest rates.
For increasing salary vs investing: do these really funge against each other? Why not both? Generically I'd think income should dominate before you have a lot invested, and then investment strategy becomes important once your yearly average investment returns become similar in scale to your yearly income.
Increasing labor income vs investing is not 100% fungible but there are some tradeoffs, especially being self-employed. Any time I spend to learn or manage finance stuff is time I could have spent working. And at least in principle there should be opportunities to spend money to increase my income, but it's a lot more unpredictable--I could advertise, in a non-pandemic environment I could join associations or go to events where I might meet lucrative clients, I could hire lower paid staff and take on clients who it is not worthwhile for me personally to pe...
Hmmm in order of certainty
1. Save and invest more = more total returns.
2. Diversification is the only free lunch in finance.
3. A cautious approach to tilting investments in favour of various factors has a lot of evidence around it. See e.g. this blog https://alphaarchitect.com/alpha-architect-white-papers/
4. Strict adherence to dollar cost averaging. Much harder to do than it looks.
Also all the personal finance rules apply - avoid unprofitable debt, take out insurance. avoid financial catastrophes like divorce, maximize marketable job skills, save hard.
In order of certainty, here are the bad ideas
1. Thinking that you can easily beat the market. Maybe with 70 hour weeks for many years... read hundreds of books and papers... otherwise assume you have negative skill to the tune of 4-6% per annum. Also going into the markets with psychological weaknesses unresolved and/or cognitive and emotional biases not dealt with - the markets have ways to find and exploit them all.
2. Investing in high cost funds based on recent outperformance.
3. Suddenly deciding to invest it all on stocks "for the long run" after a period of outperformance.
The one advantage I do have over the market is more risk tolerance. I don't assume I can beat it on a risk-adjusted basis, but since I disvalue risk less than normal ppl do, beating it in absolute expected value terms is fine, and even EMH says there should be opportunity to get higher returns that way. Will take a look at the alpha architect paper.
Leverage can give arbitrarily high returns at arbitrarily high risk. With things easily available at a brokerage, this goes up to very high returns with insane risk. See St. Petersburg paradox for an illustration of what insane risk means. I like the variant where you continually bet everything on heads in an infinite series of fair coin tosses, doubling the bet if you win, so that for the originally invested $100 you get back the same $100 in expectation at each step (at first step, $200 with probability 1/2 and $0 with probability 1/2; by the third step, $800 with probability 1/8 and $0 with probability 7/8), yet you are guaranteed to eventually lose everything.
Diversification, if done correctly, reduces risk at the expense of some reduction in returns. At which point increasing leverage to move the risk back up to where it was originally increases returns to a level above what they were originally. Diversification without leverage can make things worse, because it reduces returns.
Not making use of leverage is an arbitrary choice, it's unlikely to be optimal. For any given situation, there's almost certainly some level of leverage that's better than 1 (it might be higher or lower than 1). There are various heuristics for figuring out what to do, like Sharpe ratios and Kelly betting. As an outsider to finance, it was initially hard for me to make sense of this, as discussion of the heuristics is usually fairly unprincipled and relies on fluency with many finance-specific concepts. A math-heavy finance-agnostic path to this is to work out something along the lines of Black–Scholes model starting from expected utility maximization and geometric Brownian motion. For actual decisions, calculation through Monte Carlo simulations rather than analytical solutions lets utility functions, taxes, and other details be formulated more flexibly/straightforwardly.
Investing some money in Bitcoin would not be a bad idea. Bitcoin is both high-risk and high-potential.
I'm interested in the possibility but it doesn't have enough of a history for me to be able to think about it usefully. What is the broader reference class I should be looking at, and what is the evidence on historical returns for that class?
I still have some remaining bitcoin, from the olden days when mortal man could mine it themselves. My advice to everyone I've ever talked to regarding bitcoin is to avoid it. I have been slowly divesting my holdings.
My rationale is that while both the dollar and bitcoin are fiat currencies, bitcoin is far, far less anchored to reality than most 'normal' currencies. The dollar and the euro at least have people trying to keep monetary levels somewhat tied to physical economic value. The value of bitcoin, meanwhile is largely driven by...
My expenses are well below my income; I'm done saving for retirement
Note that a simple FIRE heuristic giving about 3% chance of running out of money at some point is to have 30x yearly expenses in 100% stock index with no leverage, which is a lot more than the usual impression along the lines of "my expenses are well below my income" and is still not something that can be reasonably described as safe.
I am far away from retirement so not at 30x yet. But assuming 7% real returns, my projected nest egg is about 108x my current living expenses around the age I want to retire. If something goes wrong before then I can always put more in. Compounding is fucking magic if you start it in your early 20s.
(This feels more like a dragon hoard than retirement savings, something that should only form as an incidental byproduct of doing what you actually value, or else under an expectation of an increase in yearly expenses.)
Haha. I didn't really know what was a reasonable amount to save when I started because I had just gotten my first real job and really had no idea how expensive a lifestyle I might want in the future. But I knew I didn't want to be poor ever again. So I set a fairly arbitrary goal, spent a few more years living on the poverty-level income I had had before getting a good job so that I could save while it still had lots and lots of time to grow, and now it's done.
And from a stress/flexibility standpoint I think it was the right decision. I probably don't have to think about saving ever again, except for fun, so if I want to take a job that is funner but pays less, I have absolute freedom to do that.
And it turns out even having money I can live pretty cheap. There were only a few material things I hated about being poor. The constant stress over money was the real problem most of the time. I don't enjoy cooking and the food was boring when I couldn't afford restaurants, so I eat more takeout. And walking 5 miles bc the bus doesn't go where you want kinda sucks, so I take more cabs/ubers/lyfts.
I am not smart enough to be a real rationalist
Nobody is. It's been a point of rather protracted discussion and great contention of late.
I am not smart enough to be a real rationalist, and I am really lazy. But I am smart enough to understand and implement rationalist advice and I suspect y'all are a better source of advice than normal investors. What is the highest level of returns I can achieve with a buy and hold strategy of some kind, across any asset class, and what is the empirical evidence for this? Also, I am self-employed, in a field where the 99th percentile earners make 7 figures per year and I make only low six figures. So how should I assess investment in an asset vs trying to invest in my career? I am not quite risk-neutral but pretty close to it. My expenses are well below my income; I'm done saving for retirement; further investing is just a game at this point. But I don't know how to play it.