Killing is not something that should be enjoyed or as an end product to aspire to, but done as something that was absolutely necessary for the survival of self or others;
hunting white tail deer for venison is acceptable killing, done to feed the family or perhaps bring in additional supplementary income where it can be done.
Likewise, killing in justified self-defense is also morally acceptable, if perhaps legally questionable, as different jurisdictions have their own dictates on how to deal with active and aggressive threat actors.
In my own anecdotal experience, anyone, be they convicted murderer or Special forces operator, who specifically speaks highly and enthusiastically of the killing aspect of what they did (emphasis: at the detriment to their other life experiences as a human being, i.e. getting a college degree, becoming a Journeyman trades worker), is deeply disturbed and a damaged person.
This isn't to say we should cast them out with indifference and disgust, but rather, to recognize they are damaged, and I would hope, that they get the help that they need.