Where is the money coming from in high stakes poker?

[GoCubsGo]

I've been thinking about this for a while. At SSNL, most players suck. They saw the WSOP on TV and they've got $200 burning a hole through their pocket. They make a deposit and after about a month, sometimes less, go bust. This makes it pretty easy for a decent player to win at low stakes.

However, these guys don't go to 5/10 or 10/20 tables. They can't afford it. My picture of high stakes poker is the same people seeing each other every day because that's what they do for a living. All high stakes players must be very good, right? I would think they just pass $ back and forth, with no donkeys constantly contributing. In addition, the casino takes a rake, so there is less and less money between these good players.

I'm obviously wrong, because people do make money at high stakes. I just don't understand how. How could there be a losing player at 5/10? Wouldn't you have to be a complete idiot to continue losing $1000 a day? What am I missing?