If there were not suffering available for them to alleviate, how would they maintain their self image as philanthropists?
I have no question that most would deny it, by the way, but in most cases I think their denials would fail under even cursory examination.
Oh sure, I don't think most would want the world to be quickly transformed into a post-scarcity utopia - that would cost them their social status. But I don't think most of them consider the suffering of the poor to be desireable in itself, or something that should be increased.