Because so few people make an actual long term commitment to what they're building, the ones that do have a huge advantage.
Employees will only add more value over time.
The second part of how to hire: try not to.
Losing focus is another way that founders get off track.
The other piece besides focus for execution is intensity. Startups only work at a fairly intense level.
Developing a personal connection with anyone you're trying to do a big deal with is really important.