Everyone's different. Check out this guy: https://en.wikipedia.org/wiki/Elliott_Carter https://en.wikipedia.org/wiki/Elliott_Carter He died at 103, still wor

Everyone's different. Check out this guy: https://en.wikipedia.org/wiki/Elliott_Carter https://en.wikipedia.org/wiki/Elliott_Carter He died at 103, still working (composing). Not many composers get stuff they wrote in their 60s and 70's described as their "middle period". Pierre Boulez just died at 90, still working (until very recently). If you're from a privileged background (and let's be honest; most developers are) there's no reason why you can't pause at 40 or 50 and decide what to do next with no fear of burnout or senility. Some people just get bored of programming, or decide that it's just more fun playing with their kids or whatever. You can always pick up a laptop and start a new project in a new language. You'll never be able to play with your favourite daughter as a five year old again.