In gambling wins only those who organize it. A person who makes bets can win from time to time, but if you count the amount of losses and winnings for all the time, the calculations will not be in favor of the person.
Gambling should be considered only as entertainment and not to spend large sums of money, then everything will be fine with you.
In simple term, the win made by the gambling house will be higher than that of the winning made by the gamblers. Every gambling script is developed in such a way with increased house edge. Different gambling websites give us with varied probabilities of winnings but the house edge of every site will be high than the players winning to assure profit for them.