They are easier to access and you can repeat them as much as you want with no limitations to how available they are, I think that's why virtual sports gambling became a thing because it was the only way sports gambling could try to make up for that difference in availability so it's understandable to say that slot games are more addictive but that's also mostly because of how accessable they are, you mostly don't have to worry about strategy, it's all just luck.
I also think easy accessibility is the biggest reason why slot are very addictive, you don't need any strategy or beginners guide anybody can enter a casino and start playing slot immediately because it is very easy. Slot is addictive and if you're not careful you will spend far more time than you planned for because you can keep going without knowing that you're late for other engagements, I think it's the most popular casino game. Unlike sports bet and other games that you have to wait to know whether you've won or not slot gives you instant results.
Exactly, it doesn't take too much time but that's exactly the trick it uses to make gamblers spend too much time on it, you can play as many different rounds as possible in very little time, this is enough to make you keep going but every single round piles up on the previous until you have spent too much time on it and the best trick about it is that there are many different slot games so you don't get bored easily, if you get bored of one you can always move on the the next.