Why do famous British people want to be in America?

All I see whenever I'm on Perez Hilton, there's a British person wanting to crack America, like Cheryl Cole- who the hell is she?. Make it big here. Why can't they stay in england? Maybe its becuz America is the land of opportunity of the world and they want Some opportunity? Plus england is a very small and tight country, it's about the size of Tenessee lol You can't even drive there, the streets are like so small.