[rndrnd]

Look, I agree with your suggestions. But each of the things you suggest (improve yourself, become full stack, maintain mental elasticity) falls in the category "try harder". That only works with things you can control.

There are also things you cannot control - changes to your brain as you get older, the kinds of jobs that are available, what other computer programmers specialize in. These are your odds.

Your success is a function of your efforts and your odds. Success = f(try harder, your odds). Since you are human, you can choose your path, and it doesn't make sense to choose a path where the odds decline so dramatically as you get to 46 ... 58 ... 63 ...