Generally speaking, bigger problems tend to be cheaper to solve (i.e. solving them will yield more utilons per dollar); so if there is a painting in a museum that risks being sold, and there are people that risk dying from malaria, the existence of latter is a good indication that worrying about the former isn't the most effective use of a given amount of resources. (“Concentrate on the high-order bits” -- Umesh Vazirani.) But in this particular case, that heuristic doesn't seem to work (unless I'm overestimating the cost of prosthetics).