Betting your team will win the tournament has a very delayed reward: the game needs to play out for hours/minutes before you know if you have won. Only hardcore gamblers experience instant rewards and becoming a 'serious' sports gambler is no easy task: you have learn about the sport, then teams, the players, the outcomes, the time of the matches, etc. Cassinos, on the other hand, are just an app with a lever that provides instantaneous rewards and thus hook your brain with much more intensity in a shorter time span. A lot of people who don't care about sports or just won't be hooked by sports betting are now trapped in those online cassinos. It's a shame.