It seems to me you can care about having sex without having the pleasure as well as care about not stubbing your toe without the pain. Caring about helping other people without the altruistic high? No problem.

I was addressing timujin's original comment, where he professed to desiring the altruistic high while being indifferent to other people, which on the face of it is paradoxical. Perhaps, I speculate, noticing that the feeling is a thing distinct from what the feeling is about has led him to interpret this as discovering that he doesn't care about the latter.

Or, it also occurs to me, perhaps he is experiencing the physical feeling without the connection to action, as when people taking morphine report that they still feel the pain, but it no longer hurts.

Brains can go wrong in all sorts of ways.