Actually, we know about the risk, but we forget it after enjoying the game, which makes us spend more money and lose more. Before we gamble, we must have control over ourselves to control when the situation is not right for us. We will become rush in playing gambling, especially if we know that we already lose some money, which can make us drag inside the gambling.
one thing is knowing with our heads
a totally different thing is applying what we know.
if one has difficulty to control their emotions the best would be separating a fixed amount of money, preferentially no more than 1% of total money that they'd be willing to lose and would be fine with.
Not many people can think about separating some money to be used for gambling, especially if they already losses in previous games. But that is still advisable to every gambler, so they can prevent the big losses, and their sadness will not be too big. As long as they know how to prevent more losses, they can save their money. Maybe it is about how we can control ourselves and the money that we will use to gamble.