This post is broken up into two parts. You can read part one here.
You are both happiest and most effective when you are so absorbed in what you are doing that for a while you forget the limited being that is actually performing it. - G.H. Hardy
Mathematics is a young person's game, or so it is said. Galois, who laid the foundations of abstract algebra, died at twenty-one. Abel, who the Abel Prize (the "Nobel Prize of mathematics") is named after, died at twenty-six. Ramanujan, a mathematical genius from India with no formal training in pure math, died at thirty-three. Riemann, of the famous Riemann Hypothesis and countless other contributions, at forty. (Is this argument falling prey to survivorship bias?)
Computer science seems no different. This phenomenon is most evident in software engineers, which tend to skew younger. You have examples like Bill Gates and Mark Zuckerberg, who were 19 when they started their companies. Peter Thiel famously started the Thiel Fellowship, which paid talented young people to drop out of college to pursue startup ideas.
While the hypothesis is unproven and most likely not significant, I believe young people have some advantages. Younger people are more willing to try new ideas, even before they are valuable. They aren't weighed down by dead dogma and are more likely to reject the status quo. In software, programmers can go faster and further with the accrued advantage of using new tools and methods. Young people have fewer distractions and more opportunities for deep focus.
The trends in longevity and leisure time might reverse this trend (if it even exists). People are living longer and healthier. As a result, we generally have more time to pursue our interests. For every Bill Gates or Mark Zuckerberg, there is a counter-example like John Carmack. Maybe the trend is directionally correct, but our definition of 'young' will change.