Yea, it isn't the nicest thing to do, but I have made considerable amounts by buying famous peoples names and then reselling the name. The only problem I've ever really had was with Hard Rock Cafe threatening to sue me, but they never did.
Jennifer Love Hewitt was my last 'client', and while I didn't 'cash in' I certainly was well paid... Considering I only owned jennifer-love-hewitt.com and jenniferlovehewitt.net. Speaking of, she still owes me a 'care package'.
So yes it is possible and there is not an entirely LOT they can do about it... Of course I sell the names for fairly cheap ($500-$3k) to avoid court, but considering what I have in each name ($7-$70 per domain) they have proven to be great investments. As one who does this sort of thing from time to time I've some advice, be prepared to deal with threats and attorneys and annoying people playing God trying to negotiate something they know nothing about. Though I've not actually had to 'retain' one myself (for these matters at least), attorneys are probably ideal for the wise and serious 'domain pirate(s)'. Though like most problems I've found they usually work themselves out if you've the stomache and time to deal with details and annoyances.