While they are very visually appealing with their metallic and iridescent coloration, it's true that they're rather short-lived as adults in comparison to many other beetle species, which is an adaptation related to the brief wet season of their natural habitats. The US species of Chrysina spend most of their lives as larvae or in pupal cells, and then only have a maximum of perhaps 8 weeks in which to reproduce, and many don't survive for more than 6 weeks at most. In that respect, I suppose they might be better suited as a rearing project for hobbyists that just want to work with something novel and not often reared in captivity, rather than keep them as "pets", in the way that you could a longer-lived rhino or stag beetle. Also, captive rearing is a good way to get perfect Chrysina specimens for collections, of course.