These markets are set up in a way to explicitly follow the current federal laws. I don't see why anyone would have a problem with these marketplaces, some may consider it gambling but in all cases the element of randomness is far less than a coin flip. You can research for as long as you wish before making a prediction. As long as the game being played is not a game of coin flip or on a random outcome, then these markets have a place where those who do the most research or have the most correct research can and do succeed. These markets can even be used as a tool for financial hedging. Lets say you have a restaurant outside a stadium, and you know if the team wins you will get $10,000 in income but if they lose people go straight home and you will only get $2,000. Let's say odds are 50% in the market, then you can simply place a $4,000 bet on that team LOSING, now if they lose you make $4,000+$2,000 or $6,000, but if they win you make only $6,000 in restaurant income. You just "hedged" and now the prediction market helped you drastically smooth our your income and lower your risk, the exact opposite of a gamble.