That's not entirely true. Yes, the salaries of the players and coaching/training staff are all paid by the parent club, but the cost of putting on the games (ushers, support staff, concessions) are paid by the minor league club, who also keep the gate revenue and any media rights. Most minor league clubs are owned by those who seek to make money from them, just as the major league club owners seek to make money (at least most of them). That's why they spend so much time thinking up promotions and trying to improve the game-day experience, because they want repeat customers. When I was in central Illinois I attended a lunch at which the owner of the Peoria Chiefs (low-A affiliate of St. Louis at the time) gave a good description of how the relationship with the parent club worked. That's why minor league team owners get uneasy/annoyed when the players sent by the parent have several losing seasons in a row - that depresses attendance and cuts into the revenue/profits of the local club owner. There has been a growing trend for major league clubs to buy/own their own affiliates (I think the Atlanta Braves own all of theirs) and that may one day become the norm, but it's not yet.