I try to give other drivers the benefit of the doubt. Maybe they're having a bad day. Maybe they just made a mistake, either out of momentary inattentiveness or simple wrong judgment. Maybe, quite likely indeed, they have no idea what it's like to drive a large, heavy vehicle that just can't accelerate or brake or turn as well as a car, and are acting out of ignorance. It helps me stay calm when I remember the odd times when I've managed to pull some boneheaded moves when driving, generally due to just being a fallible human being.
Possibly the other drivers are nasty and want nothing more than to pick a fight with you or get you mad. Often the best way to get back at such people is to kill them (so to speak) with kindness. Even if that's not the natural tendency, a respect for one's own safety should suggest that continuing to drive courteously and predictably and safely is best. (That's one reason why it never made any sense to me to blind an oncoming driver who fails to dim their lights with one's own high beams. Surely it's saner to have one driver who can see what's going on than to have none.)