Gambling is supposed to be a game of fun but unfortunately a lot of persons take it to be a source of finance which is logically wrong. Yes gambling arguably can be tempting to be a source of income especially when you tend to make multiple wins consecutively which could make one feel the need to take more days off work since you have become richer at an easier pace. The core reason people should not take gambling as a financial source is because people tend to be very serious when it comes to their finance which of course us their main income source.
Now if gambling becomes a source of income you will tend to gamble more so logically you could win more and most of the time this could end badly and even lead to a nasty addiction in some cases.
I agree with what you said, it's better that you play gambling for fun than you play gambling to make money. It is difficult to make gambling a source of income because we know that there is no certainty in gambling whether you will win or lose. The first thing that will happen to you is that your money will run out, you will become addicted to gambling etc. You will not get rich immediately from gambling always remember that so don't be serious about gambling, just play according to your budget and have fun. It's really tempting when you often win gambling, but you have to control yourself because it's not always like that, it's rare to win big in gambling.