Without getting to Rancor Pit-y; if a person realizes that in order for all the society to improve, you cannot get everything you want, then that is why you support policies that seem to "hurt" you and your class. And not just to get a kick-back at some later date, either.
Yeah, it's the whole "ask not what your country can do for you, ask what you can do for your country" thing. Which isn't really political since it can be applied to both sides of the argument.
Civilized men are more discourteous than savages because they know they can be impolite without having their skulls split. - Robert E. Howard