I have the perception slots is one of the gambling games we have lowest control over the gameplay. There isn't much freedom to configure the game as you want. It's different from a dice game, where you can bet from 1 satoshi on, while playing with the odds as you wish. Slots work 100% in function of extra/bonus spins which you can buy for hundreds or thousands of dollars. Without those special spins which boost your rolls with extra multipliers, you just lose money.
In my opinion, the visual aspect is the main reason why people feel so excited and tempted to play these games, added to the huge multiplier bonus, since it looks fascinating withall those colors, icons and brights alive on your screen.
I think that the main element of attraction and the appearance of the desire to spin again is that visually the player gets a picture where he sees that if he got a slightly different symbol (or a couple of symbols), he would win a lot of money. This creates the illusion that a win is near and forces him to keep playing. Although in fact he was not even close to winning and his further attempts have the same low probability as the first ones.