Elmtree, I grew up in a turbulent, violent family. To me it was the norm. Needless to say, I then went on to choose abusive partners and I also abused them. It was the only kind of love I knew; I didn't find out until I was 35 that not all men hit their wives.
After that I did some work on myself - clearly not enough, as I then got into an emotionally abusive relationship. This kind of covert, manipulative abuse went right past my radar but ended as turbulently as the others.
I want to be able to tell you I'm fixed, but the truth is I don't know. I'm scared to test my changes! I have never sat down and thought "Now, how can I crush Fred's ego?" or the like - and I don't believe my earlier partners plotted that way about me. There was, however, a current of mutual contempt (alongside the 'love') in all my relationships. I see that in my siblings' marriages, too: they are sick relationships. Their children have the same behavioural-psychological issues that we had.
I do believe my second H, the manipulative one, is personality disordered ("mad" in old-fashioned speak) and sees other people as no more than game characters - where he is the controller. My father was almost certainly a psycho/sociopath; he had trouble believing he was real, never mind anybody else!
In "Why Does He Do That?", Lundy Bancroft tells how he entered the field of DV as an anger management counsellor. As his courses progressed, he came to the shocking realisation that the men in his groups were doing it on purpose. The answer to the title question, briefly, is "Because they get away with it." My Dad used to say he wouldn't be a bully if anyone could stop him (duh!) - which, mad as he was, I suppose amounts to the same thing.
With apologies for my long-windedness, I think the answer is what we've repeated so often in the NPD & Stately Home threads: it doesn't matter whether there's a clinical name for it, or not. Abusers only know how to care about themselves and are happy to damage others for their own satisfaction. They won't stop because they don't have to. Some of them are pathologically incapable of stopping.
As to what you said about 'sociopaths' - well, around 12% of Americans & Europeans are diagnosed with a Personality Disorder. Bear in mind that diagnosis only happens when a person is sectioned or self-refers for treatment. Add to this the fact that most people with a PD believe there's nothing wrong with them (it's a symptom) ... and you've got a whole lot of undiagnosed nutters rampaging around, leaving their trails of human destruction. Few of them have any incentive to change.
Sorry, that was more of a ramble than a clarification! If you think you are being abused, the only safe response is to get yourself out of the abuser's sphere of influence.