Love the underpants gnomes reference and I agree that many startups will fail. But wow, working at a company you feel in your bones will fail seems to me to be a poor way to spend a career.

Not that every company I've worked at succeeded, but I hoped that every startup I joined as an employee would.

Now, as a contractor or consulting company, you still want the client to succeed, but it's much easier to be arms-length, take orders, and collect your check.