1. I don't think Lebron cares that much about money, compared to the chance to enhance his legacy with championships. There are other, better options for that in other cities;
2. Lebron will probably get a 6 year deal in a sign-and-trade anyway, because if Lebron makes it clear that he's leaving, Cleveland isn't going to be stupid / stubborn. They'll take the compensation.
3. Yes, Lebron cares about image, but that image will be quickly repaired by championships. Do people really look down upon Shaq for leaving Orlando for LA? I don't think so.