There's a valid comparison if you are gambling based on your skills.

Problem is, the majority of the gamblers do not use their skills, they tend to rely on their luck more and they are undisciplined, so you can really expect that problem will occur over time which is what creates an addiction. Day trading is different, before you enter into day trading, you already understand the risk and your chances, you don't play the game by just doing some random choices, you choose your strategy based on the information you gathered and the experience your earn.