To a degree, yes. But the word is "individualist" rather than "selfish." Able to think for yourself instead of constantly seeking validation, feedback and consensus.

You can be a consensus-type CEO later in the lifecycle of a company, but entrepreneurs must have a highly individualist view of what they are doing, and an able to cajole, sweet-talk and steer people to their way of thinking. You must influence more than you are influenced. Otherwise the vision gets diluted and eventually slaughtered by competing ideas and useless builds put in to make others happy. I've never met an exception. Even among those who listen a lot, solicit feedback, run voting exercises etc., ultimately drive things by an individual vision.

Ruthless? Yes. Ruthless in my mind simply means being willing to make the hard choices, and accepting the pain personally, and taking responsibility for the pain to others, but being willing to cause such pain to others anyway. It does not mean being wantonly destructive or cruel for the hell of it.

Even the apparently nice and soft-spoken types at the top (as Anon User says, the flashy sociopaths aren't the ones who drive startups generally; it is the quieter ones) are steely-nerved behind their pleasant and self-effacing personas. When push comes to shove, they'll make the tough calls.