All rich in comparison, sure, but most of us are probably struggling to maintain our lifestyle or investing in a better future for ourselves and/or loved ones. Atleast some of which is keeping up with the Joneses. Issue now becomes a matter of resources. How much time, energy, finances, patience do you have left over to help strangers in another country? How do you justify (to your peers aswell as yourself) aiding foreigners before your own?
Billionaires likely have a very similar situation going on. Just on a very incomprehensible level due to how far away their class is from lower and middle. Do they have as good of an excuse, though? From the outside looking in, I doubt it. Maybe the necessary security and cost of housing (why would they live in a poor neighborhood and risk burglary or death?) brings their finances down further than we realize. Would explain why they avoid taxes so much, but that's some benefit of the doubt shit. They could just be greedy as hell and have a class culture that encourages it along with wasteful spending. Who knows. Maybe, like a classic White, they're taught to hate "the poors".