The problem with waiting until later in your career before working for "three guys in a basement" is by the time you get to that stage you are wise enough to realize that:
1) They probably have no earthly clue what they are doing.
2) They won't/can't pay you close to what you're worth.
3) The equity they want to offer you has an expected value that is far, far lower what they think it is and is in no way going to make up for the paycut you will take.
4) They are no smarter and have no better ideas than you so why the heck not just start your own company instead?
I guess my point is, as you get older, you kinda come to the conclusion that working for other people's startups isn't all that it is cracked up to be.
I feel like any startup I could found wouldn't be one I'd find interesting to work at. My former boss was a PhD with decades of expertise in his field. Working for him was an experience I couldn't have made happen myself.
I'd also add that as you get older you tend to have more responsibilities like kids or a mortgage, which can be difficult to handle in the unstable world of early stage companies.
1) They probably have no earthly clue what they are doing.
2) They won't/can't pay you close to what you're worth.
3) The equity they want to offer you has an expected value that is far, far lower what they think it is and is in no way going to make up for the paycut you will take.
4) They are no smarter and have no better ideas than you so why the heck not just start your own company instead?
I guess my point is, as you get older, you kinda come to the conclusion that working for other people's startups isn't all that it is cracked up to be.