I have a black box!!!!!!!

I HATE drivers who are so focused on going faster than everyone else on the road. In my country our government has decided to put a 20mph limit on every other road and because I have a black box in my car, I have to go the speed limit. It's mostly annoying on my way to school, people overtake and make gestures at me for doing the speed limit. yesterday, someone in a van came right up my ass, overtook without indicating, while we were going into a 40mph road, so obviously I sped up to go the speed limit. They struggled to overtake me and then proceeded to DO THE SPEED LIMIT IN FRONT OF ME??? genuinely what was the point...? Just because I'm going 20 in a 20 doesn't mean I'm gonna keep doing 20 in a 40!?!?!?? it really pisses me off when people get mad at me because genuinely if you want I will go faster, but you will be getting a bill for the difference in my insurance like