The house always wins because even if a player wins one or two games he will be losing in other games. The fact that lower odds are provided or a team is tip to win doesn't mean you will win.
Well, this is what gambling is all about and of course its more on a business side so expect that every gambling sites their goal is to make huge profit coming from the gamblers. If you really want to lose big money then know how to control yourself, and play a game that the gambling house will not win much from you, for example the sport betting or any other games that you think is more profitable.
As long as you don't play too long and you are winning and cashed it out, you are technically a winner.
However, if you play longer time and even while having lots of winning already, tendency is you are going to lose because of the house edge advantage.
The moment you play longer in gambling, the more chance of losing because in gambling if you play longer you will become addict and the money you've got will be gone later on. Better not to gamble at all, and look for other opportunities in this market.