Well, plenty of people actually do put in that kind of voluntary creative or caring labor when they don’t expect a financial benefit from it.
I’m not disagreeing with you that financial benefits are a very powerful and widespread form of incentive, or that the capitalist aspects of a mixed economy often perform a useful role in harnessing those incentives to drive development and innovation. I just think you’re unnecessarily painting yourself into a corner if you try to claim that only financial benefits constitute an adequate motive for anybody to throw themselves into long periods of all-consuming devotion to work.