high roller 
noun informal, chiefly North American
A person who gambles or spends large sums of money: corporate jets still ferry in high rollers to the tables of Caesar’s Palace...
- State regulators on July 10 approved the MGM Grand Hotel Casino's application for Nevada's first private gambling salon for high rollers.
- Think casino gambling and you think high rollers playing high-stakes games, dropping thousands of dollars a night.
- Named after the Tipperary stud farm they own, it refers to a group of immensely rich Irish high rollers who are gamblers by nature, trade and inclination.
Derivatives
high-rolling
- He's even had a role in a big movie, playing a high-rolling Japanese gambler alongside Robert De Niro in the Las Vegas mob movie Casino.
- The company intends to construct an upmarket hotel and entertainment complex that would attract high-rolling gambling tourists from Taiwan and mainland China.
- Even when gambling became above board in the eyes of the law, it was still frowned upon as either the pastime of high-rolling decadent playboys or the ruin of feckless working-class punters.
Origin
With reference to rolling dice.