I have no doubt that players get paid a lot more in Europe, but I don't think thats the only reason why they want to come like you said. Obviously Football is a career and money is essential, but top players need to play at a level that showcases their skills and keeps them interested.
Like I said before though it doesn't matter, It all depends on condition, talent and situation anyway. It's not for me to care about. I just think that the argument that European football is all about money is wrong.