You have a point, but still, if you are well-experienced in sports betting and you confine your gambling scope to certain options, you are better off, as you can win more, appreciate your skills and be proud of your decisions, and can be consistent as well. Can you say that about casino games? Heck no! Casino games are not a respecter of how brilliant you are, nor the skills you've gathered to play it, the house reigns supreme, and they only let you win when they want. You are playing against certain algorithms here that "you cannot beat," you can only be lucky to be happy with it. This is unlike in sports betting that you and the house have a 50/50 chance, as they do not have any influence on the outcome.
By mathematical and probabilistic law there are more options to win in sports betting than in a casino, in fact I don't know the probabilities, but I'm sure they must aim for it, you can't win more in a place where the house advantage influences 100% than in proactive bets where you win by knowledge, of course you can lose, but it is by knowledge, that is like saying that in trading the opportunities to win are the same as in gambling, you have to be clear about that.
Even as I agree with you with regards to the mathematical and probabilistic laws, the answer is pretty obvious on its own, and you don't need to search further because casino games are the games you play against some algorithms that havs been cleverly arranged by the bookies, so it's can't be a fair 50/50 winning between the house and the players. But this is not the same with sports betting. That fair 50/50 chance between the player and the house makes it possible for sports bettors to win more than in casino games.