Actually, I think these trolls know perfectly well that no one wants them. No one wants them in their real lives but they're too chickenshit to stand up to anyone. On here, they can talk the big talk.
You must remember that this individual has no social circle, no friends, and no prospects (witness the ridiculous amount of time he spends on here, making shit up).
Your plan is a good one though because the worst thing for a troll is that no one will repsond to him. I'm sure your efforts have affected the number of responses he gets. You should seriously consider never responding to him again.