Every Man is an Island motherfuckers realizing that No Man is an Island.
Humans specifically only were successful because of pack hunting. We died quickly in nature as individuals. Anarcho-capitalism rejects this need for each other replaced with the unsound idea that each individual can handle everything on their own.
Works great until you break your fucking ankle and realize nobody decided being a doctor was important or the only person with medical skills has decided they don't want to do business with you.
The ironic thing is that they because successful because of civilization and pack mentality, but are so conceited, they think all that infrastructure (public roads, doctors, restaurants, etc) exists simply because they exist. It's weirdly how toddlers see the universe, and why tantrums between the two groups are so similar.
Nor weird at all. It requires a social and emotional maturation process to occur before an adult can appreciate the golden rule. When this developmental process fails you have a chronological adult who is developmentally immature. One of the technical names used to refer to this outcome is narcissism. Such people have prominent narcissistic traits.