I suspect it’s quite a bit of envy, too. Our culture today allows the very wealthy to flaunt it garishly, what with the yachts, jets, multiple estates, constant travel, and all the rest. It is, honestly, a bit much, and kinda tacky (in my opinion). It can make other people feel inferior, and possibly a little hopeless and desperate. The supposed equalizing effects of communism thus seem appealing as a way to feel like a more adequate human being.
Why would I care what someone else has except to be happy for them? There is a whole section of people that want money but they don’t want to work. Their energy is divided between getting money and avoiding work. It’s why people fall for MLM’s.