^ It's not the agents, it's the record label. However, the amount of albums an artist sells does have a big impact on how much money they make. A lot of artists live off of the signing bonuses they get from labels when they sign a contract. If you are an artist that is guaranteed to sell X amount of albums in X amount of time, the record label will gives you a signing bonus based on that. Artists still do make a lot of money off of concerts, but for most, the majority of their money comes form signing bonuses.