Yeah it is a fact that you cannot win in gambling. Sometimes you will win the bet but on the next day you will lose again. The current situation of bitcoin price is like gambling. One day the price goes up and the next day it drops again. Similarly when you win bet and win some money you will gamble more and the result will always be against your expectations.
It is a fact that many people cannot earn money in gambling but even if is impossible to earn money in gambling for the majority that does not mean that it is impossible for everyone, there are some people with the necessary skills to beat the house in their own games but this can only be done in games that need some skill, games like blackjack or sports bets are perfect for this, for example it is impossible for the house to give perfect odds for every single sport bet they offer since many casinos offer thousands of games so there is bound to be some mistake in one of them and gamblers can take advantage of this.