Giok, I hear you and agree that some people are sad cases, but I feel that a number must be redeemable, the problem being in the selected method.
Some I suspect to be very young, and see us as 'THEM', a kind of authority to rebel against, safely.

Some are just provacative people, impish sods, and want to initiate an argument. Again, safely, because if they did it in a pub, they'd only do it once. One or two regular members of this site may have been like this, once.

Some may be the worst cases as you describe, but they can't be total idiots, just bitter and twisted. They often contribute in good English, after all.

I don't like the notion that I'm playing their game with them, so I try to behave as if they are naughty children who need manoeuvering into a better frame of mind. Sometimes it works, but I'm in a time zone well out of step with most members, so by the time I get on, most are in bed.