There is so much ambiguity in evaluating startups, investors rely too heavily on evaluation crutches such as being a previously successful entrepreneur. Sure there is some signal present in that metric but also a lot of noise, and I think more noise than most people admit (taking a kind of "fooled by randomness" thesis here).

It seems to me that second time entrepreneurs end up being bad for first time entrepreneurs because of it, funneling money to established successes. At least, thats the way it seems to me. A bit nepotistic. What we need is more opportunities for first time entrepreneurs, like YC.