Yes the reason they moved to china league is about the money, where they can get a lot of money since now they are not famous to play in europe.
If you are in the position to choose either fame or money then almost everyone will choose money. You are being popular as hell in china league and you get alot of money from playing in it so there is almost no reason to refuse that unless that your current club offers you more however that doesnt really stop the temptation to move