The point of Being the (Pareto) Best in the World is that you can quite easily become a true expert in X if X is a sufficiently narrow intersection of domains. For example, the best person for writing music notation software is neither a programmer nor a musician, but someone having reasonable skills in both music and programming.
This post seems to make a broader claim, namely that multi-domain expertise can improve your confidence in every single domain, even if you never face actual cross-domains problems. I find this point much less obvious. If you just want to raise a general level of overall confidence, fine. But I fail to see how your expertise in a field could possibly raise your confidence in another (unrelated) field. When your piano teacher is yelling at your terrible execution of the Well-Tempered Clavier, you can't just repeat to yourself "Screw it, I've a PhD in Computer Science!"... in order to improve, you need to actually exercise at the instrument, and your PhD isn't going to help you with that.
After ten years spent between computer science and formal music training, my overall evaluation is that formal music training will definitely not make you a better programmer in general (and vice versa). The only meaningful exception for me were the music notation software courses aimed at musicians, which I found ridiculously easy for obvious reasons.
Thanks for this post. Yes, that is mostly the idea that I am discussing here, which I think can have beyond practical and work related benefits. Mainly, that it makes one more secure and confident in their life as a whole.
Another thought related to that is that it probably makes not only for more secure personality and confidence, but also more secure career in case one field becomes more obsolete.
Your experience also fits nicely with Robin Hanson's description of how a wider range of abilities (and the interest in those) is a marker of high status: https://www.overcomingbias.com/2021/06/our-big-wealth-status-mistake.html
I have hypothesis that diversifying your interests, values and desires makes you much less insecure and anxious while boosting your confidence.
Personal Example and How Idea Came to Being
In recent months I had huge increase in my confidence in all areas of my life. But I haven't got any better at them. But my social, business, intellectual and athletic confidence is booming like never before. Anxiety and overthinking is gone, too. I care less, I am more happy and I seem to accomplish everything with so much ease. At first I thought I am just getting older so I care less and am getting naturally more secure and confident. But I wasn't happy with that as full explanation. While I am sure there might be multiple factors at play, I think diversifying my interests, values and desires did the trick.
When I was starting my gym rat journey and saw all buff guys being more jacked and stronger than me, I felt insecure. When I got into business and at some business conference I saw everyone making more zeroes per month than I did per year, it made me feel insecure. When I started cooking and I saw and tasted dishes of other cooks, it made me feel insecure about my skills.
But then came tipping point. At some point, I became slightly above average in all of those things. Never the best, but good enough than whenever I came to my gym I was richest entrepreneur, best cook, best at BJJ, knew most about quantum physics etc. Even though I wasn't strongest and best looking in my gym, I was most confident because gym wasn't my single interest from which I derived my values and self-worth. I was looking at myself as a whole of all other skills and experiences. I stopped being too focused on one single domain. And this went for all other areas. I meet with multimillionaires but I am more confident in conversation than they are, because I don't perceive myself as being worse at business than them, but as being more fit, better at BJJ, better at physics, better cook etc. etc.
What also probably accounted for such increase of confidence could be added recognition of diverse range of my new (mediocre) skills. It is funny to be worst at my BJJ class, but then being recognised as best grappler among my buddies who never did it. Or being that guy who knows lot about physics and business at my BJJ gym, while being barely among average in both fields. Being average, if you are average in enough interest things, can indeed make you the best. Or at least, most unique person in the room.
Confidence Comes from What We Value
How confident we feel seems to come from where we place our values. If we value wrong things that we can't control or can't "win, then we created situation where we cannot be confident. And worst is when all that confidence hinges on one single thing. But when our values and interests are diverse enough, it can create solid foundation of confidence on many fronts. Such diversity helps us see the contrast and gives us perspective, which makes it hard to feel insecure - insecurity is subjective feeling that is difficult to feel with more objective point of view that is forced upon us once we have broader view of the world (i.e. having more interests, values and desires).
So if your whole life is about business and it is your only interest then you will place all (or most) your values on successes from business. This makes you anxious about it and it makes you overthink, too. It will drive you into deriving most of your self-worth from your business accomplishments. Therefore your confidence and security will hinge on your relative business success (relative to arbitrary goals of yours, business people you follow etc.).
Both, confidence and insecurity come from where we look at and what we value most.
Trap of Becoming The Best (Or Placing Value On It)
Having one central value and/or interest will cause us to derive most of our perceived self-worth from it and how we compare in it with others. And there will always be someone better in any one given thing. Even the best ones are always changing so even if you manage to become best, it will be just matter of time until you can surpassed.
Paradox is that people doing best in their fields are most insecure because they are too focused on their field but there is always someone who is better than them creating feeling of insecurity.
I am seeing this often, although there are many exceptions. But I have seen this in myself, whenever I had single focus I was much more attached to it and insecure about it. But once I spread my interests and focus and where I place my values, I got more chill about it, more loose and I felt no insecurity if I screw something up or seen someone doing much better.
It's Subjective Anyway...
Imagine you get strongest at your gym with best physique anyone can imagine just to learn that someone now thinks you are dumb meathead who is compensating for something. You became the best just to be look down upon by some other group of people. Or you become best physicist and win Nobel Prize, just to learn someone now perceives you as insecure compensating nerd. You can seek status and derive confidence and security from it only if you stay locked up in certain narrow group of people. Step outside of your circle, and you will find someone looking down on you, no matter what you accomplished.
Downsides
Some will correctly notice that by spreading yourself thin you will never achieve 100% focus and mastery in one field. While this is mostly true, you would be surprised how easy and quick it is to get yourself at above average level in something. Moreover, no matter how focused you are on your AI research, fitness journey, quantum gravity, startup etc. you can't do it every waking hour! And in those spare hours you can relax by slowly and calmly learning something that interests you and eventually you become above average in it.
Trick is also in actually being interested in something else than your primary desire/value. This might be hard for some. But if you try enough things, I can pretty much guarantee you that you will find something. And every new thing usually leads to another. This will eventually create chain of interests on which you can build your confidence. And often it happens than different perspectives and insights from different interests greatly and unexpectedly amplifies progress and results in your primary thing. It's no coincidence that most of my insights for business came from fitness industry, and most of my fitness progress came from understanding science etc. You will be able to draw analogies and intersect principles that create new lenses through which you can view the world. It is like seeing in extra dimensions that give you the edge.
So downside is that you may lose some focus from primary thing. But I think upsides make up for it. You might not become the best in your field, but you can become best at your life. There are few who dedicate themselves to one thing for their whole life, but I don't think most of us want that.
Conclusion
Ultimately we all seem to know that tying our identity or self-worth to something we can't control creates feelings of insecurity. How it could be otherwise? If your security depends on something you have no control over, then of course then cannot be any confidence. If there is single point of failure, if that one thing doesn't go as desired, then there has to be anxiety.
But while we cannot have full control, especially over one single point of failure, we can have control over the whole. If we just place importance on diverse values and interests and avoid single point of failure by not attaching our desires, values and self-worth to one single thing, then out of this approach can emerge seamless confidence.
And will all that being said, this is only one part of very big and complex concepts like insecurity and confidence. For some people this might play a significant role and shift in change they seek, and for others, it can make no difference or even backfire. It is a tool that has to be used appropriately and will not apply at all times for everyone, but it is something to keep in mind, because it does exist and seems to work really well many times for many people.