Ask HN: How are meh founders becoming partners at yCombinator / 500 startups?

I have seen this happen twice now:

Someone launches a no-one-knows-about-it start-up company, and raises angel / series A funding. The company gets acquired for $5m.

Next thing I see is that the founder is now a partner at an incubator and working as a tech investor. I have seen this at both yCombinator and 500-startups. Case in point: Harj Taggar.

How is this possible? After the acquisition the founder would have barely netted $2m. Is the bar for entry to partnership at a prestigious place like YC so low?