BTW you've pretty much explained the thought process of everyone who gambles at anything regularly.
There are some people for whom gambling is a profitable profession (I was one such person), some for whom gambling is a reasonable recreational activity, some for whom it is a life-crushing addiction, and there are many shades in between.
And prohibition only makes things worse for all the actors. Professionals and amateurs alike have to play on sketchy sites that fund criminals to make their living, and people end up being exploited by the lack of regulation similar to how you might die of alcohol poisoning from moonshine you drank in a speak-easy in the 20s[2].
[1] https://en.wikipedia.org/wiki/Wikipedia:Featured_picture_can...
[2] Here's one example where a poker site stole millions of dollars from its players. There were many such cases: https://en.wikipedia.org/wiki/Cereus_Poker_Network
Casino games, against the house, and computerised "slots" are gambling games which can't be beaten long term.
Sports gambling is very different, and can be beaten. There are many, many sports bettors and traders who make steady, serious income from their bets. This is true especially when using betting exchanges, where one is betting against other people, rather than a single bookmaker. Individual bookmakers are notorious for closing winning punters' accounts. On the betting exchange, the house just take their commission from all your winnings. The successful trader factors into their strategies the platform commission.
The key for successful sports betting is the concept of value. The bettor needs to find prices which are incorrect, and over what they believe the true odds should be. If the strategy is correct, continually placing value bets will lead to long term profit.
For some people though this is just plain betting. They don't have a strategy or an angle, they just believe they might get lucky and for these people this form of behavior equates games with skill to rote gambling.