If you want to go to Kahneman & Tversky, yes different heuristics people may use for estimating risk and reward are probably biased estimators (although I hope all pirate-entrepreneurs are using a little math and obtaining feedback ). That certainly does not mean risk, independent of gains, becomes intrinsic utility for the non-masochistic.
I studied cognitive psychology not economics ;) I'm familiar with the topics your bringing up and agree they're interesting but also think they are irrelevant to the issue of correlation vs causation and the red herring of "risk" when looking at what motivates entrepreneurs.
What's the opposite of risk? Most people would say safety; but I would say boredom. Stimulation becomes repetitive if there's nothing at stake. It wasn't for the expected gain of money that I bet on games during the World Cup last summer; it was to make the games in which I had no personal stake interesting. I don't know where you are, but internet betting is legal where I am.
I don't think appetite for risk is sufficient for entrepreneurial activity; but I do think it's necessary. So I don't think it's a red herring.