Million dollar Tattoo

I learned today recently that the celebrity Kate Moss is worth a million dollar but half of that money is due to her tattoo on the lower part of her back. She has a tattoo of two doves looking at each other. In my opinon , no tattoo is worth half a million dollars. The two doves may be a symbol of something but still , I dont understand why it would be worth that much money. When she gets old is it still going to be worth that much and what if it gets removed or it starts to fade , then what?