I am beginning to suspect that it is surprisingly common for intelligent, competent adults to somehow make it through the world for a few decades while missing some ordinary skill, like mailing a physical letter, folding a fitted sheet, depositing a check, or reading a bus schedule. Since these tasks are often presented atomically - or, worse, embedded implicitly into other instructions - and it is often possible to get around the need for them, this ignorance is not self-correcting. One can Google "how to deposit a check" and similar phrases, but the sorts of instructions that crop up are often misleading, rely on entangled and potentially similarly-deficient knowledge to be understandable, or are not so much instructions as they are tips and tricks and warnings for people who already know the basic procedure. Asking other people is more effective because they can respond to requests for clarification (and physically pointing at stuff is useful too), but embarrassing, since lacking these skills as an adult is stigmatized. (They are rarely even considered skills by people who have had them for a while.)
This seems like a bad situation. And - if I am correct and gaps like these are common - then it is something of a collective action problem to handle gap-filling without undue social drama. Supposedly, we're good at collective action problems, us rationalists, right? So I propose a thread for the purpose here, with the stipulation that all replies to gap announcements are to be constructive attempts at conveying the relevant procedural knowledge. No asking "how did you manage to be X years old without knowing that?" - if the gap-haver wishes to volunteer the information, that is fine, but asking is to be considered poor form.
(And yes, I have one. It's this: how in the world do people go about the supposedly atomic action of investing in the stock market? Here I am, sitting at my computer, and suppose I want a share of Apple - there isn't a button that says "Buy Our Stock" on their website. There goes my one idea. Where do I go and what do I do there?)
I apologize, I was unclear; I'm recommending 'buy and hold indexing' where you correct imbalances by buying the stocks you have less of with new investment income, rather than correcting imbalances by selling stocks you have too much of to buy stocks you have too little of. This is a good way to invest for individual investors who have a constant influx of investment funds and who pay trading fees that are a large percentage of their order sizes.
If you have a large pool of capital that you begin with, or you want to actively manage money you've already invested, then you may want to actively correct imbalances. It's helpful to work out the expected value of a rebalancing trade, and make sure that's larger than the fees you pay (and you may decide to only rebalance once it gets above some larger threshold). Here, you do end up with mostly Netflix- but you bought a lot of Blockbuster when it was expensive, and sold it when it was cheap, whereas the projection investor who knew that Netflix was going to worth 30 times what Blockbuster would be would have put 3% of their money into Blockbuster and 97% into Netflix, and so the majority of their current shares would come from when they put a lot of money into cheap Netflix stock. I haven't heard about that sort of projection investing playing well with rebalancing- and if I remember correctly, it was designed for allocating a large pool which you have complete access to, rather than doing dollar cost averaging with a constant income stream.