When is a pedestrian a “dumb-ass prick”?

The other day, on foot, I asserted my right-of way at a junction. A van driver sped up and braked, ready to turn left, looking away from me, to his right, for approaching traffic. So he could have hit me if nothing was coming and he had carried on. So with my gloved hand, I smacked the bonnet of his van to warn him of my presence. It prompted him to wind down his window and yell, “You dumb-ass prick!” I tried to point out that pedestrians have right-of-way at junctions, but he spat back, “It’s my priority!” Thus is played out on our roads millions of vile incidents, all caused by the evils of an inadequate driving test and the dysfunctional rules of the road.