Its addicting because its fun give you a nice thrill and you earn money at the same time.
I became addicted to it when i had a 5 days winning streak on a local gambling game in my country.
Earning money is the main purpose why its addicting.
victory promising start, but after that I'm sure you will not always be lucky to win a number of occasions, doomed to defeat as well.
That is what you called beginner's luck, when you are in gambling for the 1st time, most likely you are lucky and when you win you think that gambling is really fun and still play again to push your luck without knowing that it might cause you being addicted when you cannot control yourself in the future.