Why are bikers so stupid on the road?

Last Thursday
on the 7th of August Melanie and I were driving to our mid-wife appointment.
I stopped at the intersection of 11th east and 3rd south because it was a four way stop. I looked both ways and didn't see any cars so I started to go. When I got about half way through the intersection Melanie screamed my name and then all of the sudden I heard this big thud in the back of my car. I was wondering what had hit us and when I looked back I saw a guy skidding across the pavement. I was scared out of my mind because I initially thought that this was my fault that I had hit a biker and almost killed him. Luckily this guy only had minor injuries, just a few gashes on his leg and that was it.
So the reason why I did not see the biker is because on that intersection if you are heading north on 11th east there is a big wall and trees on your right side blocking your view from seeing all the way up 3rd south which is a big hill. So apparently the biker was being stupid because he saw me stop at the stop sign and then go and for some reason he decided not to stop. He was going about 25 to 30 mph and he had no plan in stopping. He ran the stop sign and tried to swerve out of the way but he he hit me. What an idiot. Luckily there was a witness who saw the whole thing and called the police. We first thought he was against us and was going to say that it was my fault, but when he filled out his police report he said that the biker was being stupid and ran the stop sign. The biker got a ticket and he is supposed to pay for the damage of our car but so far our insurance has not been able to contact the kid to get the money. So we may be out of 500 dollars to get are car fixed. This sucks hopefully the dumb kid will pay so the car will get fixed.