I have a sense that I'm one of these people. I'm risk-averse, perhaps anxious by nature, and I like the structure that corporate entities provide, despite being well aware of how challenging it can be to exist and thrive within that structure at times; and, despite what PG writes in "You weren't meant to have a boss":
http://paulgraham.com/boss.html
It's appropriate, given his audience, that most of what PG writes is very encouraging of the idea that people should just get out there and get things going by themselves.
But, not being familiar with all of his essays, I wonder if someone could point to any that are a little bit more ambivalent about the whole endeavor.
You'll find that a lot of people here have something crazy in their genetics that makes them know that they have to do a startup. Like, they could be really happy doing whatever they're doing today, but they'll never stop thinking about how they are going to do their startup. Those are the people that pg is talking to in his essays.
If you ask me, it's about doing what makes you happy. If you prefer to have a job at an existing company, or if you're risk averse, there's absolutely nothing wrong with that.