The cost of getting an early hire wrong is really high.
... you want to be proud of how much you can get done with a small numbers of employees.
If it works out, you're going to be working on this for 10 years.
Most founders have not managed people before, and they certainly haven't managed managers.
You have to be decisive. Indecisiveness is a startup killer.
The other piece besides focus for execution is intensity. Startups only work at a fairly intense level.