Some gambling operations like the paramutual betting pool at horse tracks don't even promise any odds. The odds shift as the bets come in and the prize pool is just split up between all bettors equally -- after about 17% has been subtracted to pay for track.
With tote/paramutual betting the operators assume no risk or volatility. They're not market making. In my view it's exploitative, which I guess is why in the UK it's offered as a state run monopoly on horse racing.
With fixed-odds sports betting there is at least volatility to contend with, and the bookmakers do take a position, even if over the long term they do price to make a profit and will ban you if they think you're even remotely sharp.
Sports betting has been legal in the UK forever, including online. The US is very much behind in this industry
Of course there's a fine line (or maybe no line) between addictive and just plain fun or exciting... so I'm not sure what the solution is.
Making games less fun or exciting is not desirable, but neither is having people so addicted to games that their real-world life suffers.
