You are clinically mentally ill. Most humans have some empathy for other human beings. So when they see painful things happen to other people, the empathy circuit in their brain fires off and mirrors that experience in their mind happening to them or people they know. That is why people get upset about that--- they have empathy for their fellow human beings.
Some people overreact to shit they see or hear though. Those people are doing it as part of their social behavior to appear to other humans to be 1000 times better than you. Except for the crazy girls whose empathy circuits are fucked up and super intense. Their are a few, but they are very rare (1 in 1,000,000) so most people that over-react are just acting like cunts.