... fire fast when it's not working. It's better for the company, it's also better for the employee.

A small communication breakdown is enough for everyone to be working on slightly different things. And then you loose focus.

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

Later, you should learn to hire fast and scale up the company, but in the early days the goal should be not to hire. Not to hire.

People that are really smart and that can learn new things can almost always find a role in the company as time goes on.

Great execution is at least 10 times more important and a 100 times harder than a good idea.

Ideas by themselves are not worth anything, only executing well is what creates value.