There's more context at https://github.com/charlesfeng/startup-school-2013/blob/mast... - "You shouldn't even make friends with people you don't see starting a company with — why bother? You only have so many best friends, so use those resources wisely."
Thanks for the context. The additional context does not really make the statement any better IMHO.
Starting a company with one of your friends has a lot of "drawbacks". If your friend is underperforming by a huge margin you often don't want to risk the friendship by telling the truth.
Some of my friends have nothing to do with tech or business - most of them enjoy a very low risk way to live (employed with the state or county for example) and don't want to do it any other way. I enjoy a little bit of risk in my live. :) This different way of living does not make my friends any worse or better...
Doesn't sound like a fun way to live.