Specifically, if you're fixing to earn serious money off playing poker, your job is to SEEK OUT irrational addicts fighting personal demons, and personify said demons. You're basically looking to find prey and eat them. The wounded will be less capable of running away from you.

You could lurk outside the door and hit them with a rock or stab them with a knife, but that would be illegal. Functionally you're playing a similar role. You're stalking prey, trying to find the weak and hurt them, possibly until they die, knowing there will be more.

I quite understand why people can get off on this, but I also understand why many healthy humans will be put off by it. It's playing up one aspect of humanity while totally stifling other aspects. Humans are also cooperative, but that's not going to make you money playing poker.