That's utter nonsense.

People don't avoid starting companies because they're afraid of the capital gains tax on their anticipated profits (At least, people with a healthy dose of perspective don't do this).

If you're going to pick from the list of reasons that people avoid starting companies, at the top of the list has to be the fact that most are afraid that they'll be unable to take care of themselves and their family during the lean times. Universal health coverage is an obvious step toward alleviating this fear. The abstract, vague notion of someday paying a (rather low) tax on the eventual, theoretical profits from the venture doesn't even come close.