I believe it's mainly main character syndrome. Like when we play a game like GTA, you care more about your own stats, progress and wealth, and maybe that of other players, but couldn't care less about most of the NPCs, and that gameplay dynamic seems attractive to most people.

Another way to look at it is the higher up on the perch you are, the more everyone else looks like ants. You probably won't intentionally leave some sugar for the ants, but if they get a few you don't mind.

As for the richest of the richest of the rich, they need to stay influential for various evil reasons.

Well, it seems that dragons are real lol

It's a pissing contest. Who has the biggest number on their account.

Why hoard money?

When the fountain of youth is discovered, it's gonna be expensive.

"Sometime around the 80's. Next question."

For power, that's all they want

How many yachts can you ski behind?

Found the original, it's from Tumblr: https://www.tumblr.com/blog2g/176805334897/decayinginfrontofme-why-do-rich-people-need

I mean, all people need money but there is obviously a point where you really do have enough to live comfortably the rest of your life…

If I was a multimillionaire I'd give so much of it away. I'd LOVE to singlehandedly fund our local cafe that feeds unhoused people every day, as well as house people all over the city. Nothing would make me happier than to actually do something meaningful. I'd be embarrassed to be greedy and buy Lamborghinis and shit. Give me a nice condo and a cute Mazda and a trip a year, maybe some clothes shopping, and that's all I need to make me happy. The rest can go to improving the lives of those in need.

While I think there are limits to how much money anybody can reasonably spend, if someone works hard and makes money legally and ethically by virtue of their efforts then that's their own business. It's different of course if they made their money through crime or exploitation, and it's easy to think of examples, but that isn't the case for most people.

Also, if people perceive inequity then the answer is progressive taxation and other forms of financial remuneration to the state which can be dispersed as they see fit. If billionaires were hit with super taxes then they'd still be billionaires but it would pay for services that would raise the quality of life for everyone else.