About 10% of VC-funded companies are big successes, defined as making 10x their investment. About 20% go broke, and most of the rest end up in zombie mode, able to pay their bills but not pay off their investors.
Most founders, therefore, are doomed to be losers.
But VCs look for people who are sure they will succeed. Most of them turn out, in hindsight, to be wrong. This is inherently going to push a sizable fraction of them into mental health issues.
This is how we end up with statistics like 27% of founders have mental health issues. Source: http://www.businessinsider.com/austen-heinzs-suicide-and-dep...