high roller
From Longman Dictionary of Contemporary Englishhigh rollerˌhigh ˈroller noun [countable] American English informalSPEND MONEY someone who spends a lot of money carelessly or risks a lot of money on games, races etcFrom Longman Business Dictionaryhigh rollerˌhigh ˈroller noun [countable] informal American English someone who spends a lot of money or who risks a lot of money, especially in GAMBLING (=risking money on the results of card games, races etc)For really high rollers there is Marquis Louis Roederer Crystal champagne at $205 a bottle.