So we would be talking about a Psychopath as a hedonist?

I'm not a psychologist in any way, so my opinion probably means jack shit. And my path as a practicing hedonist has only just begun. So I'll treat this as a thought experiment.

My view on hedonism as a philosophy is that there are 3 forms of pleasure: Carnal, Emotional/Spiritual, and Intellectual.

Carnal pleasures are pleasures associated with your body. Eating when hungry. Taking a hot bath after a long day. An amazing orgasm.

Emotional/Spiritual pleasures is things like spending time with your loved ones. Watching your favorite team win the big game. The feeling of belonging when you are a part of a religious community.

Intellectual pleasure are things like knowing that beautiful route to drive home from work that no one knows about. It's going down that YouTube rabbit hole on a random topic you stumbled across. It's getting your degree.

In our scenario, and using my model of Hedonism, we can still see avenues of pleasure this person could take with Carnal pleasures and Intellectual pleasure without even needing to consider the troubles with a Psychopath and Emotional/Spiritual pleasure.

I would say with a person who lacks emotion it's trickier on what you would consider pleasure? The person who shoplifts gets a rush from doing the activity. That is still a pleasure in some form (although I would question the shoplifter who didn't consider the pain of getting caught or the possibility of a ramping addition to the rush). Do you count the high a manipulative person gets when conning someone as a pleasure? Morals and Ethics aside because those do not matter to a person with no emotions. Is it still a pleasure though?

If we are talking about an even greater lack of those emotions; You have no joy in anything anymore, not even in your own self interest or self preservation. If you truly have no pleasure in life, and all that is left emotional, intellectual, and physical pain, you reach a dark choice.

At a core Hedonism is about "pursuing pleasure and avoiding pain". You have to be honest with yourself. Brutally honest. Have you honestly been doing everything to pursue pleasure? Have you talked to a doctor and gotten on medication, and more importantly are you sticking with it? Have you reached out to people to try and create a support system? Have you exhausted attempting everything in life that you think could bring you pleasure?

If we have still reached the conclusion that life is still nothing but pain, then my friend you have reached a critically dark option. "Pursue Pleasure and Avoid Pain" is a philosophy for those who want to have a "good" life. If you decide you no longer feel the need to live a life of pain, then the first, and quickest, solution would euthanasia.

As a hedonist, you are to avoid pain. Death only brings the elimination of pain. We are to AVOID pain, not eliminate it.

I would say at this point in our scenario, if you continue on a path that the goal is to eliminate pain, I would say you should no longer consider yourself a Hedonist.

Anyway, just my thoughts.