~OP~
What protects me from foolishness in gambling is deposit limits and responsibility for my family. When I didn't have a family of my own, I could spend half my salary on gambling. Sometimes I actually did that. When I finally started a family, I stopped spending so much money on gambling, because most of the money I earn is needed to provide a decent life for my family. That's why I sincerely don't understand people who spend their last money on gambling instead of buying something necessary for their family.
Yeah, family can be our reason from stay away the foolishness that we did in the past. We may think our family need something from our income and that can hold us to spend more money in gambling. If you have a child below 5 years, you will remember his funny face and want to give something to your child. You may delay your gambling activity because of your child or family so that make you think that you don't have to spend much money in gambling because you want to use that money for your child.
The realization that we need to be financially responsible is a very good reason not to gamble foolishly, no responsible person should use significant amount to gamble because it's not a business. If you realize that winning in gambling is by luck and beyond luck there's the house edge, you wouldn't put all your hope in winning. If you know that you can be addicted to gambling if you devote more time, money and energy into it that it can ruin your life, you will learn responsible gambling. Every gambler have enough reasons why they shouldn't gamble foolishly because anyhow you look at it it won't end well for the gambler. Responsible gambling is key to mental health of every gambler.