Gambling is a type of entertainment. If gambling was a guaranteed way to earn a lot of money, everyone would quit their jobs and gamble because it is very easy and there is no need for any hard work. Whereas working requires a lot of hard work for 8-12 hours straight. Because of this, you should not bet on confidence in any field, be it sports betting or casino. Those who think their strategy has a lot of potential and think they are very clever end up ruining themselves in the end.
I think some dudes just want to gamble and make money from it because they are probably lazy to work and make money through jobs. However, like you said that gamble is for entertainment but gamblers with the opposite perspectives thinks it's the easy way to make money quickly. I agree with you that if gamble is easy many people would have stopped working and focus on gambling.