high roller

noun2

1. •
   (informal) A gambler who wagers large amounts of money, usually in a casino.

   • They were all "high rollers" against faro, had plenty of money, and, if the cards came favorably, would "chaw up" a bank in double-quick time. — 1873
2. •
   (informal) One who has a lot of money and lives luxuriously.