Would you hire someone who doesn't believe in your company?

Expand it past this one person and to the entire company: would you employ only people who don't believe in your company?

Obviously not. So don't hire one of them because they'll drag the other ones down.

People who don't believe in your company are less likely to stay for more than a year and less likely to think long-term about their work. People shouldn't be forced to crunch or be underpaid, but that still doesn't mean they should be complete mercenaries.

If you can't staff your company with people who believe in it, you have a different problem, which is: what's wrong with your company and can it be fixed?

It depends, people who 'believe' less in stuff , they are actually smarter than the believers because of course most startups go to zero and if somebody is naive then there are higher chances that they won't be as bright as a depressive realist.

So you might counterintuitively actually end up ahead by hiring the person who doesn't believe in the company, because they'd work less and with less enthusiasm but the quality of the work might be better because they are as a person better than the naive believer.

Sure. The important thing is that they are sincerely motivated to produce good work. Exactly what motivates them isn't as important as that something does.

In what sense do you mean "believe in"?