If I were an investor, I would probably have a strong bias toward 2+ founder startups. This wouldn't be because single founder startups never work, but because of "bus factor." Having two or more founders at least halves the likelihood that the single founder will in one way or another become incapacitated. This could refer to medical or personal problems or just to burnout, personality issues, etc. It's a lot of eggs in one basket.

So I suspect that investors like multiple founders because they like to reduce risk.

I also do suspect that single founder startups are at a disadvantage. You have half the networking surface area and are much more prone to getting discouraged without the moral support another person can offer. We are social beings. I'm just curious about whether the disadvantage is as extreme as PG claims. I've seen numerous counterexamples, but honestly I have yet to see any good hard vetted statistics either way. I mostly see a lot of opinion.

I guess it's a tough statistic to really gather, since there is no single central registry of tech startups.