... for the top twenty most valuable YC companies, all of them have at least two founders.

You also want to fire people who a) create office politics, and b) who are persistently negative.

Momentum and growth are the lifeblood of startups. This is probably in the top three secrets of executing well.

You really want to know your cofounders for a while, ideally years.

You need conviction in your own beliefs, and the willingness to ignore others naysaying.

Whatever the founder cares about, whatever the founders think are the key goals, that's going to be what the whole company focusses on.

You should think about for the next 10 years, you're going to be giving out 3-5% of the company every year.