Paul Buchheit: "We definitely fund [solo founders], but you have to be about 4 times as good. I think Instacart was a solo founder, and that's a great company. We're very happy to fund single founders; it's really more for your benefit. If you can possibly find someone, it really does help."

https://www.youtube.com/watch?v=ZTv4iO7e8bQ#t=15m16