Riddle: Jimmy bought a bicycle for $20. But then he figured he didn't want the bike, so he sold it for $30. Then he suddenly decided he indeed wanted that bike in the first place, so he bought it back for $40. But after some long consideration, he sold the bike again for $50. Still not able to make up his mind, he bought it back for $60, only to later sell it again for $70. Did he gain or lose money?