When you gamble and you win, your brain releases dopamine. This increases the levels of serotonin, which in turn triggers the production of oxytocin. That’s the chain of chemical reactions that causes a burst of euphoria and makes us feel happy. The problem is that levels of happiness hormones eventually drop, and if what caused the spike is the only thing we rely on in life to be happy, we may come back to a very sad and depressing reality once it’s over.