What do you think a psychopath is? Because what you seem to be describing is more like Schizoid PD, where the disordered person has a complete disinterest in other people.

I'll ignore myself for a moment since the jury's still out. The literature on psychopaths describes them as being very outgoing and involved in numerous social activities. One of the criteria is a need for stimulation, and a lot of the more exciting activities, particularly competitive activities, involve interacting with other people. Another characteristic is duping delight, and you can't get duping delight without a dupe. Even if we're only considering the practical use of others' personal information, you could easily use it for extortion purposes.

There are a lot of reasons a psychopath could be interested in another person. Their problem isn't that they're uninterested in other people; it's that they prioritize their own amusement above the other person's feelings or boundaries, and what they consider "amusing" would be considered "gaslighting" by most people.