Being a Jack of everything

I saw a question another day on Quora asking "if playing chess makes you smarter". I also saw a pretty witty answer to it claiming that the better you are at playing chess the "more stupid" you are. The guy did not want to condescend chess or chess players, he just expressed that to be a better player you need more and more time and you technically lose that time, while you could also focus on something more "useful" than chess, because playing chess only makes you a better chess player but nothing else. As long as you are not a grand-master and make a living out of chess, you are "wasting" your time. Don't get it twisted, he understood that it might be the passion of someone, and they should play then, but the question was implying that you would become an astrophysicist because of playing chess, and he is pretty right about this perspective, claiming NO, it's the other way around.

This notion had stuck in my head and I realized there is a curve for every activity, which tells us, how useful the activity is in terms of our general life. I am not in love with money and I believe life is more than that, but the easiest way to quantify this is to estimate, how much money can an activity bring us in the future. This whole idea does not apply to a passion of course. To better explain my idea, let's continue the chess example and let's look at different scales of skills, and how much time you spend on playing chess (I assume that there is a monotonic relationship between the time you invest and your skill). I believe that we get this curve for chess skill (time invested) VS efficiency:

I explain my hypotheses with a series of examples. For the sake of illustration, I use extreme cases.

Left part (negative efficiency): if you don't know how to play chess, that might be a problem in your life at some point, for instance you might meet a CEO, a professor, or whoever, who is in the position to help you in your career or project, but they don't like the fact that you don't know how to play chess (a typical intellectual thing), so they dismiss you, i.e. the negative efficiency.
Then you reach the local maximum region, where you know how to play chess, and you don't fall into the trap of the previous situation.
After that region, you start to invest more and more time into learning chess, but there is not really any positive outcome in terms of efficiency. You get the same result (being cool with the hypothetical CEO or professor), but you invested more time.
And at the right end of the scale you spend so much time, that you become a grand-master and you earn money, fame and respect, so efficiency can be super high again.

Once again, this is simplifying and I don't think money and fame is the ultimate purpose, but I believe it's illustrative. For instance, this is also true for going to the gym as well. On the very lefts side, you are either very skinny or fat and that might hinder your life in terms of finding a partner, health or even career.The lower optimum point is when you are fit, and people admire you for that, but working out more just takes away time and gets you a bulky or "over-shredded" body, that is not even that attractive to most people and can be unhealthy. However, at the right extreme, you might be a famous bodybuilder, or fitness model and you get your paycheck on your investment.

Where the two extremes and these regions are situated on the "invested time axis" depends on the activity. For playing chess you have to spend a tremendous amount of time on it to become someone who makes money of it, but concerning programming, it's considerably less time.

This is in no way a true scientific or statistical proof for anything, it is just how I perceive the world, and my career in it. I am personally multidisciplinary and spend my time on getting better in various things, programming, science, fitness, public speaking, and I do this, because I have realised that many activities don't yield more fruit after a certain point (middle region together with the optimum is actually the same as Gossen's first law), and I might better invest my time in some new directions. Of course, it might block me from becoming the greatest of all time in a given field, but it kind of ensures me that I will always have a foot to stand on. What are your opinions about this guys?