Not everyone loses in the long Run. Only those who are greedy and do not use their minds on when to stop are the one who loses in gambling. Rest who play with mind and luck never lose.
The fact is that being greedy doesnt mean that you will lose, if luck is against you then you will lose no matter if you are being greedy or not. Depends on luck however you could win a good amount. Some people are lucky, i have seen myself and kinda experienced how you could get a decent amount by winning some jackpots