Why do so many on this web site answer so spitefully? what is the need for it really?

i have seen some horrible comments against other people in need of some friendly guidance and advice. the worst was seeing horrible questions about "maddy". surely people should know better than to say such spiteful things. its just so wrong in so many ways. why cant people be kinder to others,after all its a question and answer web site not a "call and insult" site. why do they go out of there way to be horrid. serious answers please,although i suspect that some will use it to insult me. xx