Patrick is right but it goes a bit deeper than that. It would depend on the place you won it at. You have to remember it's illegal to gamble in some of the sports book in this town. The Coast properties will take a bet but the Station casinos sweat a guy betting $10 dollar show bets in their race book and you'd be run out of the sports book if you were a consistent winner. The key would be to spread the money around. If you wanted to bet $2000 on a game you just bet a nickel at four places. They all have the same numbers so it doesn't matter.
The IRS is no problem as long as you keep the total money bet under $10,000 each day and you would want to keep each bet or series of bets under $2500 because they would start logging your bets on a clipboard.
Sports betting in Las Vegas is a thing of the past. They only want square tourists playing those moronic parlay cards and the locals playing those idiotic football contests that get 50,000 entries and 500 people tie for first each week and win $12.75 a piece.
The IRS wouldn't be the problem but dealing with the clowns running these sports books and all the aggrevation trying to get from place to place and fighting the tourists will stress you out so much, you'll lose your patience and your edge. If you're talking about the numbers that you mentioned, open up 3 or 4 offshore accounts and bet with places that will let you gamble.