@cshentrup economists use expectation over Von Neumann–Morgenstern utility functions ("expected utility") to characterize risk preferences. lots of people would take a guarantee of 1M over a 50% chance of 3M, suggesting they are risk averse. the fact people are willing to forego in expectation 0.5M is an interesting observation about actual human preferences. it's hard to express that without saying that, over this range, the person who chooses 1M prefers certainty or lack of risk.