It's addictive cause in your mind you think you can win alot of money and they always make it seem super attractive on those gambling sites, so really its not your fault its the human mind being addicted to this kind of stuff lol
Especially those who has won the jackpot or so, the casino will make sure that they will advertise extremely so that everyone who came into the casino will know about it. In this way, it will let you believe that it is possible to be the next one to win the jackpot and you will end up playing more and more for that hope.