It's best not to tangle with idiots ... you see them on the roads, you see them on motorcycles, driving BMWs or Mercs in Taipei, thinking they are driving some sort of spaceship ... AVOID. If they do something dumb, or you try to stop them doing something dumb (like driving like a real A*****e...), you will not be thanked at the time, especially if you are right.
I've had several drivers flash lights at me on the roads in Taipei, speed up, slow down, suddenly switch lanes in front of me, or otherwise try to crash my car on the roads in Bali (always)... but for my caution. Why did they do it? Just because they were in the wrong place at the wrong time, and they were idiots. Unfortunately, standing up for your rights is only going to get you trouble, at least at that point. Fortunately, I have always assumed that the person in front of me can do anything at any time... so I avoided those idiots.
I'm planning to get a webcam on my car, so at least I can record the incidents next time. Perhaps... that will assuage me