I had heard about the Sweet Peach episode but did not realize that someone committed suicide after it. Not to dismiss the "put on a successful face" factor in Silicon Valley but I sort of think that is less of an issue than some more structural things.

* One common factor in young people I know who've killed themselves is that they are very headstrong: their friends are afraid to get involved because they seem to know what they're doing, or they are known for cutting off people who get in their way. You can see how this trait would be strongly selected for in founders, for better and for worse.

* Another is that founders often find themselves wedged into a situation where all of their closest confidantes are somehow dependent upon their success, which makes it awkward to talk about anything potentially bumming.

* Also a lot of younger founders in particular have never really failed at anything big -- despite the Silicon Valley obsession with failing fast and a lot, founders aren't as practiced at failing big as they think. In many cases they were their parents' pride and joy, always the most brilliant student at school, got into the most competitive colleges, went to work for Google, then broke out of the engineering pack to found a company that raised venture money. If you don't know what it feels like to fail at something that is your whole identity... you don't know.

* And finally, founders are strongly selected to be PROBLEM SOLVERS. See a problem, solve a problem. When the "problem" is that your life seems super sucky... what's the fix?

One big problem that you don't mention is that everyone else spins (and lies!) to make themselves seem more successful than they actually are. Anyone who takes the successes of others too literally is going to make himself or herself even more depressed. 

That's only true if you compare yourself to others. You can be suicidal for other reasons.

True. No reason to make it worse comparing yourself to others. 

And in general it's a good idea not to let other people let you down. 

I wonder if there's something about proclivity for depression that also makes someone more suitable for founding a company. 

This came to mind for me too. It has to be that certain 'personalities' (whatever that means!) are attracted to it...

There are many theories of depression: that it's an evolutionary adaptation that was necessary for our ancestors to survive, that it's caused by inflammation, and that it correlates with creativity.

I've been collecting these observations and theories over the years:

http://pandawhale.com/ifindkarma/depression

What's clear to me is that, debilitating though it may be, depression is something a lot of founders grapple with. And those founders really do need help (both professional and personal) to deal with depression -- they cannot just hope it takes care of itself.

Is there a kind of kamikaze spirit among some startup founders: betting there whole life on their company projects?

What's important enough in building a company that makes your life not worth anymore if you failed it?

Money? need of acknowledgment? need to feel like you have a purpose in your society?

Some combination of those, yes. I think you're right.