Why have infinite willpower if not to use it to satisfy preferences? Smell the roses, play games, chat with friends. The only reason not to do this on any large scale is if there was something you had to do now that could have huge returns later. Code a self-improving AI, discover immortality, that sort of thing. However, even with infinite willpower I don't think everyone is cut out for that, so for most people I'd say make enough money to hit diminishing returns on investing it in research, invest it in research, and live the good life.