I think mostly it's learnt behaviour, possibly been treated this way and learnt to do the same. We're fairly blank slates from birth, and then learn as we go what then becomes "normal" to use. Everyone's early years are different, and as we get more experience outside the family bubble we're exposed to other ideas.
Not everyone recognises the bad habits they've been given, or perhaps only some, and pass them on to their children. Some bad habits, particularly domineering power-based ones, are also tempting to retain due to perceived advantages for those skilled in using them. Some people will have suffered the effects of them growing up, increasing their vulnerability to people who've grown up to be good at using them.
Similar things can happen at any stage of life, but I think upbringing is a significant period. There's probably genetic factors in there, the importance of that vs nurture is keenly contested.
I'm sure lots of people will disagree, it's what I believe from what I read tho & just a rough summary of my understanding 😁
You are best rid of him tho, none of it is your problem, he sounds awful