Yes, most of the people at the top are billionaires. Tony Bloom owns Brighton FC, Benter is a billionaire (probably, he made several hundred million in HK), Billy Walters is likely close, Ranogajec, Alan Woods is close, Benham is likely close (or was before he decided to buy several football clubs).

The issue, as I said initially, is that you aren't scalable past $100m or so (without connections to the Asian books, which some people above have...apparently, some of the guys are able to put down multiple millions on most European soccer leagues...which isn't available to most). But yes, most of the funds run by the above people have been making 100%+ for years.

It's solid. The problem is scaling: if you're betting fixed odds, a lot of bookmakers will limit the amount you can bet, or ban you outright if you're winning too much. If you're into horses and bet into the totes, you run the risk of wildly affecting the pool (and therefore the final payout) if you're throwing huge amounts into it. The only way to really scale it is to bet into pools that are already huge (like Hong Kong - hence why it's such a popular target for the big syndicates).

Parent comment said you can't scale.

Sports betting is huge. this is not 30 years ago. you can easily scale millions into bets/ and most ppl would be very happy to make $30 million out of $5k or so over a decade.