How many people would worship God if they didn't think he could give them anything?

I've occasionally seen televangelists who preach the "gospel of prosperity" and promise their gullible flocks that if they send in money, they will have health and wealth, too. The fraudulent behavior of the televangelists aside, how many of their followers would actually love or worship God if they didn't think he could give them something? Correct me if I'm wrong, but isn't their behavior sort of like that of a bratty kid who only loves his parents if they give him a car and a cell phone?