"Could this be at least in part a self-fulfilling prophecy? Due to the way healthcare is set up in the U.S., the only people who really can consider quitting their jobs, and losing their group-health plan as a result, are: 1) people who are already rich (or have rich family); and 2) healthy young men"

Health care is a small part of it. The other part is that once you have a stable income and a family (wife+kids), most people don't want to take the risk of losing that income because the risk will have lasting effects on their entire family. When you are young and have no dependents, you can take this risk.

This is why you should get your company started first..and then settle down with a wife+kids.

Or go gay. You know. Either/or.

Serious point though: It's relatively easy to take risks on your income when you're half of a DINK family.

Being gay no longer automatically avoids the married with kids & big expensive house problem, at least not in Silicon Valley.

I'd have figured closet marriages would be less common now, especially in the bay area, excepting senators/televangelists I suppose. Or are you referring to adoption? Ugh kids.

The "need to support a family" argument may explain why founders are young men, but not why they are young men.