Where do they get the money?

Yup, maybe.

I think a lot of what folks are writing and thinking here is due to perception. We as people generally believe that normal is what we are used to seeing everyday. Then when we go someplace different we are somewhat, perhaps subconsciously, shocked that so many people can be different.
There are a lot of very rich young people out there in the world. Some of them even earned their wealth themselves. Before my partial retirement I had hundreds (well, more than 100) executive level people working for me, most of them quite young, and they are very well paid. Then there is the outside support. Financial planners, stock brokers, insurance brokers, bankers, lawyers, doctors. And that's just one small corporation. My wife's firm hires 50 to 100 people fresh out of law school every year. This years first year associate class starts at $160,000 plus bonus, for a 25 year old kid. Take this and multiply it by the many thousands of big and medium companies out there. Even subtracting those that don't fit the stereotype we are talking about, but concentrate them in a party magnet such as Vegas and it is not hard to understand.

You wouldn't think it would be hard to understand.