There are so many artists that do this. I blame the publicists and management more so than the singer themselves though. I doubt as if 90% of the time they even know what country they will be performing in, let alone who they are performing for. With that said, I don't think 90% of them would back out if they did know for that kind of money.
Sting, Beyonce, Hilary Swank. They're either willfully delusional, or thick as shit.