Just like other businesses or like a shopping mall. There is no how you will tell.me that you beat the shopping mall after shopping. Even if you are given a loyalty card which you shop with, there is no discount. They are simply reducing the price of some products and increasing some and give you at what seems to be a cheap price, which is not in a real sense.
So, we all lose on a long run and the business owner takes the profit while we take satisfaction which could be fun for gamblers.
Exactly, we may save some money if we buy when there is a discount or when we receive some kind of bonus for our purchases, but stores do not sell their products for a loss, and the same is true for casinos, running a casino is expensive as their owners have to hire programmers, customer support, rent servers and many other things, and as such they cannot offer the services of their casinos for free, but instead of charging directly like a regular store they use the house edge to keep themselves in business, and as we can see it works very well as only a minority can beat the casino with regularity.