Why do I feel sad for a stranger's death?

Humans are social creatures. A good human is one that can understand the feelings of others and in turn feel for them a certain way. That is why when we come across sociopaths we deem them mentally ill. Because as a human we have feelings that allow us to work together and be together. Or subconsciously at first you compared this to the situation of your friend and that stranger in your eyes was like your friend subconsciously, and now consciously too.

Just think about other things, he/she's dead now, you worrying about them won't bring them back.

That my friend is called empathy and compassion. To feel toward someone you don't know, thats great! What a heart you have, but on the downside- it can allow you to get taken advantage of-im speaking from personal experience. It happens to me all the time, but i cant help it.

Because we as human beings are programmed for empathy. I wept, straight out sobbed, when Benjamin Breedlove, whom I had never met but whose videos I had seen, ended up losing his battle and dying of heart failure.

https://www.youtube.com/watch?v=tmlTHfVaU9o

https://www.youtube.com/watch?v=a4LSEXsvRAI

https://www.youtube.com/watch?v=WDM5fjvF9jY

No one else is mourning his loss so someone else becomes sad.