Well, in my point of view, generalization wouldn't ever bring you to "ultimate 100% truth", even if you gathered much information, as there are many aspects.
For example, even a psychopath is also a human being – unless you categorize it as humans/organic portals/psychopaths, but nevertheless, people always have different personality types, experiences, coping mechanisms, etc.
Therefore, your point of view will evolve because you will hear about something different in a different context, you will guess, and you will add.
But in the end, you'll have some general idea, even if it's complex. If you apply this lens to a real person, many things will be true, but you'll still see a rather complex generalization, not a specific person. And if we look at a group of psychopaths, it will be funny.
It seems to me that the scientific approach means that one must rely either on thorough individual experience, with the awareness that it is selective, or on broader research, taking into account that they may also generalize somewhat or be wrong for other reasons.
But of course, you're free to have your own thoughts and research. That doesn't mean you always have to stick strictly to the facts and can't have your own ideas, because that could drive you crazy and turn you into a bit of a cyborg.
True psychopaths have an absence of feeling – well. What do you consider feeling? What about anger, a sense of injustice, superiority, desire, or revenge? Or sympathy, pleasure. They are said to be incapable of feeling love or compassion, but why then can they be loyal? Or, if they cannot feel love, why can they feel hatred? Even animals possess emotions, at least at a cognitive level. I'd say that it's impossible to function "normally" without any feelings whatsoever.
In order to fit in to society they have to "act" in order to be accepted as some version of normal – I think we need to distinguish between situations that require acting. For example, Jeffrey Epstein testifying in court or giving an interview. And everyday situations, even public ones, where one nonetheless functions spontaneously. Adapting, reading the situation, and reacting (calmly or impulsively). In other words, it seems to me that a "psychopathic mode" may involve more intense activity and doesn't necessarily have to be a 24-hour mask. Not to mention the tendency to reveal one's cards out of boredom.
Besides, where did you get the idea that they are "empty vessels"? For example, have you talked to one, read research, have you got that feeling, or are you taking it from films? You say it with such certainty, as if you'd just established a paradigm. I'm not denying it, and I'm not saying it's not true, but it's a strong statement and would require support. Starting from a false premise, you'll reach false conclusions. For example, it would be safer to say "mostly empty vessels," but then we're creating a picture based on something plausible. Even if shallow, or a narrow range, or certain forms, I guess they have feelings, along with personality, thoughts, etc.
I think too, there is a difference between emotional empathy and intellectual empathy. Psychopaths don't have it in either form – I totally don't agree with that part. For various reasons. But to name a few: "human characteristics," "adaptive needs," "current state of knowledge," "my own feeling." (Simply, denying intellectual/cognitive empathy in psychopaths contradicts the scientific understanding and common sense).
Besides, I don't know if psychopaths are worth thinking about so much. But in the context of what you're saying – their susceptibility to programming – it seems to me that they're not particularly attached to their beliefs. It's simply easier for them to find their place among followers, gain a position among them, and enjoy the complexity. But probably also don't care if it's unnecessary.
Your vision is more like bots from the Matrix or alien clones ready to act like cyborgs. Mine is closer to someone like Hans Landa in the movie. Evil, but ready to abandon his employers' views when the war ends because he no longer needs them. At the same time, narcissistic and full of wishful thinking – he genuinely believes his plan will work and everyone else will buy into it.
But that's obviously a striking example. In reality, you can have psychopaths who aren't particularly conspicuous: politicians or philanthropists who pretend to be good people because they give people bread, moralistic priests, troublesome acquaintances who have always been around you and don't really have any remarkable status or make that much of an impression, because although the symptoms are obvious, they're not Hannibal Lecter. Or institutional leaders who are simply reliable and composed, and you probably wouldn't call them that. Like James Fallon, a psychiatrist who actually has psychopathic traits but probably has never hurt anyone.
It seems to me that your thinking works more like this: "A rather pretty, smiling woman supports her diplomat husband, and then sleeps with his murderers. That's impossible; she must be programmed." (Empathy leads to a sensible interpretation from an empathetic viewpoint.)
And then he tried to convince me that they might admit me to this psychiatric facility I was working at. I responded that they couldn't do that because "I was too old", so he floated off to see if he could 'spook' anyone else out. 
