It's too easy to say "just be self-disciplined."
Nobody knows all his inner demons. We perfectly see the weaknesses of others and their examples from life are always obvious and simple for us, but in fact we ourselves have neither the ability to look at ourselves from the outside nor self-control. Imagine that you won a large sum with the first bet.
Will your inner state remain the same?
I wrote that it's better to keep friends around, or write down your limit, or have only cash. The next time I go to the casino, I will definitely follow these rules, because you need to be especially strict with yourself.
That's exactly the thing, having self-control or staying within your limits is not as easy as one might think it is because if you are gambling regularly, you will probably find it hard to maintain a limit if you haven't been practicing that from the beginning. When someone wins a big amount or maybe loses more than they can afford to, that is when they don't remember about any limit or have any self-control, they will either become greedy and want more or will become angry and try to recover their losses.
And we all know what happens in both situations. When you get greedy, you will most probably lose what you have managed to win so far which is unfortunate, of course. When you become angry or emotional, you will deposit more money and try to recover your losses and lose that as well in most cases.
There are always difficulties when we make a decision, but we will not know how difficult it will be when we do it. Often, what we think is difficult is not as difficult as we imagine, so we don't want to do it. It is indeed difficult to control ourselves, but if we don't try, we will never know how difficult it is. When we can win big, we must immediately stop gambling, and even though there are thoughts of continuing to win because we want a bigger win, we will not be tempted and prefer to stop gambling and enjoy our winnings. But when we prefer to continue gambling, we are likely to lose, and the loss will be bigger if we lose control.