[ispolin]

One way to answer that might be to look inside ourselves.

Take me for example. I indulge myself with books, songs, apps, etc. Granted, it's on a completely different financial scale than Hermes bags, but I own more things than I can realistically consume. So let's call whatever I buy but can't consume "excess".

Whatever instinct causes me to buy stuff in excess instead of using that excess to help the poor more than I currently do is likely the same instinct that causes the rich to buy 4000 shoes and 100 Hermes bags instead of helping the poor more.

I don't introspect enough to know what that instinct is, but most of us here probably have similar very minor excesses in our lives and can get some clues by thinking about those.