Fish at high stakes games

[Ianco15]

I have never played any limit above 3/6 and I have a question for those who have played limits much higher. In high stakes games such as 100/200 or 1000/2000 or even middle limit games like 30/60, where do the fish come from? Who is going to sit at these limits that is not a winning player? Clearly not every one playing at this limits is a winning player, so what are people thinking that sit at these limits and routinely lose? Are these people just so rich that they don't care?