Why do some people ignorantly insist that everyone's life has value?

Wow! when i read the title i was gonna get on the defensive and state that everyones life has value unless you are some kind of eugenic nazi, but after reading that i would like to see the end of that murdous &%*> people like that have no remorse and will not change. However wanting to inflict pain on him and kill him in such a manner... does that make you/me just as bad? almost. Do you fight evil with evil? an eye for an eye? i'm not sure.