Depends on a lot of things, like I said it truly is all over the place. Certain arbitrators are going to go with the celebrity no matter what, the name doesn't have to be for sale, etc... Some celebs show that they have built up a common law trademark in their name, or they will make an offer. Oliver Stone paid $6,000 and gave a signed copy of his latest script. You just don't know, the celeb can go the other route and skip the UDRP and go straight to court where most domainers or fans cannot afford to defend the name. If the name makes you no money and the celebrity won't buy it, how does it make sense to spend money to defend the domain name ?
There is no set rule you can stick to, you can't say look at OliverStone.com he paid money, or if you don't monetize it you are guaranteed to keep. There is nothing 100%.