Jake’s statement here is evidence of the cynicism that he ultimately finds overwhelming.
As a character, Jake is something of a “realist” from the start, yet there is a divide in him. He has a romantic yearning, a sentimentality that takes the form of hope. He hopes he might get to have a real relationship with Brett, the woman he loves.
At the same time, Jake knows that Brett will never say yes to that sort of relationship with him, in part because of his injury and in part because he is not extremely wealthy. Potency is what attracts Brett to men and it is virility and wealth which, for her, define potency. Jake has neither and he knows it.
The struggle between hope and cynicism regarding Brett is large enough within Jake’s context to be generalized to his entire world view, as we see in the quote. When Jake finally feels he must give up on Brett, he suggests (in this quote) that there is no chance of happiness. That is not part of the “emotional economy” in which he exists.
He has to deal with the economical limits of his emotional world, which means that best he can hope for is that his (emotional) efforts receive at least some kind return.