You have to find a small market in which you can get a monopoly and then quickly expand.
In YC's case, the number one cause of early death for startups is cofounder blowups.
So always keep momentum, it's this prime directive for managing a startup.
As you grow, the productivity I think, goes down with the square of the number of employees if you don't make an effort.
You want to continue to be run by great products, not process for it's own sake.
Why couldn't it have been done 2 years ago, and why will 2 years in the future be too late?