I've seen people go out of their way to console others who are terminally ill. People have raised money for others who lose their income due to illness. They've supported each other through diseases, new parenthood, loss of jobs, divorces, and natural disaster. I've even seen an online community rally around a lawyer who lost everything in a moving van fire. If an outpouring of kindness towards a lawyer isn't the best of humanity, I don't know what is.
People online can be horrendously cruel and clueless.
A friend of mine was stalked by her ex-husband who followed her everywhere online just so she would know he could. Others hide behind anonymity to wreck havoc on reputations and to say things they are too cowardly to say otherwise. When the Holocaust isn't being watered down for someone's pet peeve, free speech is used as an excuse to behave like a jerk. It's easy to move way too fast in online relationships. It often amazes me how people craving intimacy will rush to disclose everything about themselves in their first five posts.