I am also jealous of people that won hundreds of BTC on gambling sites.. so I always try to bet and see if I get lucky enough.. never happened.
When you see someone to bet and win, it does not mean that your bit will also give you a win. Try to learn about gambling. There require a tricky knowledge to earn at there . So first you play without betting your money so that you become expert at that games.
Gambling can be fun if you have guts and many capital so you can conqueror the gamble and make some insane profit.
But the matter is everybody's luck are different so we can predict our luck everytime