someone who spends a lot of money carelessly or risks a lot of money on games, races etc
A high roller, also referred to as a whale in the casino industry, is a gambler who wagers large amounts of money. Because of potential windfall these high sums can bring to the casinos, high rollers often receive increasingly lavish perks from casinos to lure them onto their gambling floors, such as free private jet transfers, limousine use and be allowed to stay in the casinos best suite