The value of their team rises, they don't have risk any of their own money on a facility. Here government is protecting the owners from the folly of their bidding up of salaries beyond what the fans of the team can or are willing to pay to see the team. They really don't have a problem with their revenues, they have too much in expenses. The state charters them and gives them legal protection. Big corporations love big government.
Big government protects big corporations from competition.
Big corporations can buy favors from big government. I accidentally dropped a few lines from the original post. When the state grants the corporation it is creating an artificial person who will live in perpetuity. This artificial person can enter into contracts, sue and be sued. At the same time the state granted corporation shields its owners from most personal responsibility for the actions of the corporation.