You have to understand that the money in this case, the money won, is not hard earned money so it becomes very easy to play it again and lose practically everything. Honestly this is the main reason.
When you get caught up in gambling and become addicted, it happens because your spirit is out of alignment and this causes imbalances that you try to compensate with the adrenaline of the game.
Don't expect much from gambling, but if you win eventually don't misuse because it came in as what you never worked for, calculate how many times you've deposited and lost, does it correspond to what the house has gotten and what you made out. The best way to see your win from gambling is not how perfect you are with the predictions, out of all the options offered by bookies, and it chooses to favor your selections, luck is an essential determinant, since the outcomes are usually unforeseen till it happens.