I truly hope that in 15 years, when I am celebrating my 25 year anniversary, I wont lay awake at 4am and think about what I could have done better…
You can't hold on to these things, but they'll bounce around your head sometimes, when life gets more challenging.
That being said, it's also balanced by a lot of good memories. Not so often at this time of the night, the small hours, but nonetheless a fond memory will strike you now and then. The time when you came through clutch, or the project really went amazing even though everything went wrong, the time you helped an intern gain confidence and they went on to do amazing things. The small moments when you helped someone solve a problem and they returned the favor, that's what makes the job worth doing.
In your obituary, when your life is tallied, nobody who matters is likely to give two figs about your work projects.
I’m only a bit further into my career than the person you’re responding to, but this sounds truly depressing and (personally) incredibly unlikely. I’ve been in the situation where I was offered a spot at a company which later got acquired for a few billion dollars. I barely ever think about it, and when I do it’s simply as a “huh! Life is weird!” kinda thing. It’s not something that weighs on me and never has been. I really can’t emphasize enough how little of a regret it is.
Maybe I’d feel differently if I was worried about becoming fabulously wealthy, but that’s always seemed like a fool’s errand to me. It’s much easier to be happy if you just aspire to have enough money to take care of yourself, your family, and at hopefully contribute to your community a bit.
Totally agree on the interpersonal stuff though.