In the long run you likely have more chance of winning money from sport betting than you do from playing at a casino. Every game in a casino is engineered to eventually move all your money into the casinos pocket by basic mathematical odds. At least with sports betting the casino are reduced to taking an educated guess, based on a lot of number crunching of previous statistics on the outcome of the game with a nice buffer built in for them to secure a profit. If you stay away from multi-bets, which is where casinos make most of their profits, then you stand a fair chance of success if you closely follow sport and are able to distinguish profitable bets due to surrounding factors (weather, a good player being out, etc.)
This is self-deception - in fact, in sports betting, the bookmaker's margin is greater than that of the casino in most games. And the longer the distance, the less likely you are to be smarter than the bookmaker. The only advantage of sports betting is arbitrage bets and all sorts of boosters and bonuses (but in fact they only reduce the bookmaker's margin to the average casino margin).
The house edge can in fact be very high when it comes to sport bets, so not only the punter needs to be very skilled in the particular sport they have chosen to make a few bets, they also need to identify which one of the bets has the smallest edge or try to catch some odds which may be out of place due to punters favoring one team too strongly, all of this makes incredibly complicated for anyone to obtain profits long term from the activity, even if there are a few people out there which can do this.