If someone got involved and you didn't want him. The choice is yours. You either tell him you don't want him at all (whilst you want his money) or you keep him under the false illusion in order to take his money but your conscious bothers you a lot. At least, he made it clear to you and you would have to come clean sooner or later. In a way, this isn't too far from ordinary dating. The guy liked you but you didn't'. It's better to tell him soon rather than keep him hanging around.