You don't need to wait till you're at your deathbed. You can do this assessment every 5-10 years. When you're past 40, you've lived quite a bit. You can look back and see what was worth it and what wasn't.

For me, stuff I regretted wasting time on while younger (e.g. too many video games) bring back much better memories than doing things I (mistakenly) thought had more value. Quitting gaming in my early 20's was, in retrospect, not a great idea.

But yeah, I agree with you somewhat. A lot of people who live to a fairly old age actually have said that if you live long enough, you'll realize that "nothing matters". So probably not best to put too much weight on their perspective.