Why is the Seminole Tribe so rich?

AFFINITY Bank National Association 21 AMERICAN Bank National Association 3 BlueHarbor Bank 8 Cogent Bank 20 EAGLEBANK 13 Fieldpoint Private Bank & Trust 4 First American State Bank 6 First Bank of Okarche 3 First National Bank of Nokomis 2 Frontier Bank of Texas 11 Hamilton Bank 12 Kinmundy Bank 18 Legence Bank 9 Neighbors Bank 7 SALLIE MAE Bank 26 Sanborn Savings Bank 3 Security State Bank of Aitkin 9 Shell Lake State Bank 11 South Louisiana Bank 4 Wheaton College Trust Company, National Association 26