Badawais,
I agree, if you're going to drive at 20km/hour on the fast(?) lane then you should make way for others.

But, if the person in front of you on the fast lane, is driving fast enough within the speed limit then, you DO NOT have the right to flash your lights and speed up as if the next minute you're going to bump the car off the road.

I'm not sure if that's the case here, but in most other civilised countries, driving past the speed limit would be called breaking the law.