I think it comes down to how much time you spend playing and not necessarily how many games you play. If you are mentally strong enough, it's not going to matter if you play only one game or experiment with a few different ones. But if gambling is all someone thinks about and the only happiness they experience is betting on the next game, then I agree with you that they are heading down a dark path.
That can be considered addiction. A person that only thinks is to gamble is bound to destroy his life. He just bet mindlessly since he enjoys the pleasure of doing it but diesn't cinsider the risks if his action.
That is why setting a limit when gambling is important. Not only in terms if time but also on budget that you spend when gambling. Having a limit teaches you to discipline yourself knowing when to stop in gambling. It prevents you losing more money and fall into addiction.