It is like that because you win money, and people like money
What is that? it is like what? people dont always win in every round even they saying that they are playing it in the smartes way people are being addicted because they losing money and always chasing it people like risking money always.
That's the design of gambling, to put the players most often in losses of money and winning is very seldom to be happen for the gamblers. Even if they win, it will be the reason for them to stay more in gambling for thinking they will win a lot but in the end all their winning amount will be gone.