A sociopath might be manipulative, but they are also shallow, and frequently more than a little dumb. Take those sweeping generalizations with a mine of salt as most of what we know about the population comes from research conducted in the prison system. A satanist and a sociopath diverge in that a satanist tends to be a sensitive type, deeply attached to life, curious, and thinks about the consequences of their actions. I have no data to back that up, other than my own assuredly inaccurate self assessment and equally problematic hunch about the general satanic zeitgeist. The satanist realizes that people, like machines, can be used to do things for them that they would rather not, or cannot do themselves. Both groups are united in their conscious use of people.
You can use a person for sex, as an emotional outlet, a political connection, labor, protection, and so and and so forth ad infinitum. Personally, I like to cultivate semi-distant though affectionate relationships with people from a variety of social castes with the outlook of an investor. Sure, this conversation, this movie, or this blowjob might not be fun now (rhetorically of course; I've never met a blowjob I didn't like, and if I ever met a blowjob I would ask how it managed to ascend from a thing done to a thing that is) but this time that I give to this person now will appreciate in the bank account of their memory. It may accumulate more time than I put in, and I will be in the position to demand more time from that person than I gave to them, or the time might change to something like cash when I'm in a jam, a ride when I'm pickled, or a joke when I'm sad. But I do not disregard the feelings of others, I factor feelings into my social calculus when manipulating folks. Furthermore I don't think that what I do is much different from what anybody else living in any human society does. We leverage our relationships to get shit. Sociopaths tend not to give anything back in trade, and take a short view of the exploitable relationship. They take the big shiny thing and blow the whole thing up rather than slowly drain people around them when it's needed, giving something back every now and then. Sociopaths drive their cars until the wheels fall off. I lovingly maintain my car; I change the oil, rotate the tires, and other things. This is a poor analogy because I know nothing about cars, though I understand that they require some upkeep. I maintain my human machines. If I don't, I would end up doing those things that I don't want to do.
Obviously, there are folks out there, like Machiavelli, Lau Tzu, and a bunch of others who've written far more effectively about the methods of manipulating people. But what can we learn from the bastards, the psychic vampires, the dreughs, and the human leeches that abound. They get along in the world through their drainage, and I can respect that in a certain sense. I think I would die of embarassment before moving back to my parents, going on the dole, living off of someone else or something. But if could erase that part of my brain, maybe I'd be the real winner at life.