Just imagine finding a USB stick on the street, all crushed by passing cars, and taking it home, repairing it, and discovering that it contained the private key to thousands of BTC. Wet dream?
What would suck is finding a wallet.dat containing the addresses which display thousands of BTC, but then realizing it was encrypted and of course you don't know the password, and it could be short or long, but probably at least 20 characters so you just know you'll never crack it. (Or it could just be a watch only wallet, and there are no private keys at all.)
What I'd like to find is an Opendime on the street, and then discover it has been preloaded with thousand of BTC. (or just hundreds.)
Or some bronze metal plate, the size of a credit card, with 12~24 words stamped on it ...
Or an envelope with a one sheet of paper, printed with a QR code ...