I think angel investing is cool precisely because it is a bad investment. Ashton Kutcher could give all of his money to a responsible financial planner but why not gamble some on the next big thing? AirBNB seems like a good choice for him to bet on, and they'll benefit from his notoriety.
From what I've seen Ashton Kutcher tends to invest in companies that make tech that he really wants use. I don't think profit is really the number one thing on his mind - he already has money. And since it was revealed that he was involved in the Skype deal I bet his portfolio isn't hurting anyway.
