Let't not say that it's the end of a career if one walked away while in the CFI stage. That's not a career. It's just getting started and doing something else.
There's no shame in finding your own path.
Your thread title is misleading, but it appears that you're attempting to say you want to talk about what happens between the end of a "flying career" and the end of one's life. Presumably something other than flying. That's not the way the title reads, however, and it nearly suggests that the end of a flying career is the end of life. It's not.
Flying is not for everyone. There's nothing wrong with doing something else. If flying is missed, do it privately, instead of a career. If it's not missed, don't do it at all. Neither is wrong. Do what works for you.