It takes zero effort for the brain to process this and hence it is what the body likes to do which is why these games are so addictive. There are other games like dice which also follow the same procedure and hence always addictive if played for quite some time.
The games thag need some thinking like sports betting and poker they dont necessarily yield well to the ones with intelligence but specific skills related to that game. Of which I think sports does carry a lot of luck factor in it.
I personally enjoy playing poker sometimes, but there's no real money involved. Honestly, I prefer playing it in person with my friends because I find poker quite fun and brain-boosting. Although it can be challenging and requires skill, I enjoy playing it despite my limited skills.
In any form of gambling, luck is involved, even in games that emphasize skill and knowledge, it's still closely tied to luck.