[epistasis]

I think another huge factor is the network of people you know and the breadth of knowledge you can tap into that way.

Superstar young founders have crowds coming to them to fill those gaps, but less high profile young founders don't have access to that.

I would think that a very astute person starting their first startup in their 40s, but with tons of connections and deep knowledge in the target market, would have an easier time than a generalist that had done ton of startups but with less connection to the target market. But that's a broad heuristic which may have nearly as many exceptions to the rule as data supporting it...