Success of the startup depends a lot on the industry it is in:

http://www.amazon.com/Illusions-Entrepreneurship-Costly-Entrepreneurs-Investors/dp/0300113315

That book is actually pretty optimistic for Silicon Valley type stuff if you read it.

Startups that get venture capital tend to have high expected values:

http://80000hours.org/blog/12-salary-or-startup-how-do-gooders-can-gain-more-from-risky-careers

To be frank, I think most entrepreneurs are naïve and incompetent (this is from hanging out in online entrepreneurship communities and going to events for entrepreneurs). As an entrepreneurial type, most entrepreneurial types annoy me. (The stereotypical example would be a college entrepreneurship club that doesn't result in the creation of any new companies. Also, try any nonprogrammer that wants to start a web company, or anyone who complains about being rejected from Y Combinator – being rejected isn't a sure sign of failure, but complaining probably is – the appropriate response is surely either stoicism or defiance :D) I'm sure that a driven less wrong user has a significantly better chance of succeeding than the median entrepreneur.