I hope that my opinion about trolls is worthwhile, and hopefully will be corrected if it's not. What I observed, but didn't hear directly stated: trolls feel threatened.
For whatever reason, unfamiliarity sends some folks into a state of neurosis, an upsetting of their equilibrium.
I think of a troll partly in the case of the Three Billy Goats sense: the troll is an owner of a critical pathway. He collects tolls (tribute) a/or has a reputation to uphold in performing his daily routine. He is defining and defending the status quo. If he sees that you wish to build a new alternative (bridge), this threatens his current monopoly. Instead of scaling his current operations and building new bridges, outsourcing the admin of them, and franchising the operation, he wants NO NEW BRIDGES. Perhaps he inherited his power, or wrested it away in a primitive sense. Any evolution of methods that doesn't go the way he likes, he will thwart, dismiss, or destroy. Perhaps it's bullying, not to defend the troll, but to see things from his perspective: he was bullied, and overcame bullies to get where he is now. All he sees are threats and he doesn't want to play any new games. If you owned the phone lines, perhaps you're seeing wireless that way.
To return to your point: trolls aren't interested in learning new things about stuff outside their field. They aren't nomadic like the goats, so they see goats as merely trespassers, competitors, or as victims. Not as neighbors, partners, or customers. That would take a more open mind.
Part of rudeness is not knowing how really rude one is; the other part is not caring. Back to the old joke of when the punk is asked "are you ignorant or apathetic ?" he replies "I don't know and I don't care !" Perhaps it's natural that trolls see life as a zero-sum competition.