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.