Yes, this scam is live and well in the sports betting world. There is even a CNBC reality TV show called "Money Talks" that documents and encourages this; as documented by the show:
https://www.youtube.com/watch?v=0xiiv-s-DRs http://www.vipsportslasvegas.com/The recipe is:
1. Cold call people on a lead sheet for people indicate interest on placing bets on sports games.
2. Sell interested folks with a "two week package" for $250; seems pricey, but the name of the game is to filter out the minnows catch gullible whales. You want folks who are "vested" on this and prove they have the cash to be scammed. Double-side your bets or smarter yet, side your bets by the probability implied by the Vegas oddsmakers (50% Team One Wins, 50% Team Two Wins or 70% Team One Wins, 30% Team two if spread is that way).
3. After a couple of weeks pass, call up the people who have won 4 or 5 games in a row, inevitable happenstance by sheer probability. Upsell them on a "weekend Vegas package" where they can gamble on higher stakes preferably $50K-$75K; because you're seem now as a infallible genius by the marks, you charge them a 35%-50% commission on their wins.
4. Doesn't matter if your client wins or lose. Take home the 50% commission on their churn and move onto the next one. Rinse and repeat.
The show is highly entertaining and enlightening not because of the extreme doucheness of the head scammer and his salesmen, but the marks who delude themselves as they lose game after game and gets scammed - all followed by the camera-men of CNBC and the spin-motivational commentary of the scammers.