Every game in which you play against casino favors the casino. It is completely normal. No matter if it is roulette, blackjack,
baccarat or whatever else you will lose in a long run. Every game where everything depends on luck like lottery, bingo and so on gives you very thin chance to win in general.
Regarding sports betting - many people think that just like poker there is skill involved in sports betting too. This is not exactly correct. In poker there are two elements that you can use in your favor. One of it is the monitoring of the other players on the table and trying to get some information which you can use in your favor. The other is your own play which is helped by using the information from your analyze. In sports betting you only have the first component available - you can get some information to base your predictions on but you can not effectively influence anything.
I personally treat poker as game of skill with elements of luck. Sports betting is something between poker and games based on pure luck. My personal advice would be to treat sports betting as pure gambling and not invest money that you can not afford to loose on it.