I can't remember what the worst bet I ever made was, but one of the best / easiest would be betting that this [Double or Nothing] guy wins.
IMO it's a lure scam.

Just imagine,

1. The hotel pays this guy $10,000 grand plus comps.

2. They follow him around, videoing him [prior] while he "supposedly" sells his junk.

3. He rolls into Vegas for his 1 spin of the wheel.

4. 50,000,000 people are watching this on TV

5. Table's probably gigged to win.

6. The guy wins, [but not really] followed by a crowd roaring party.

7. Every wannabe "sucker" sees this, then thinks how wonderful life would be with a one roll fortune.

8. The reservation phones start lighting up like a Christmas Tree.

If they run bets on a win / lose, take the win.
I'll be surprised if he loses, sounds too much like a Stupak deal.