Humans will do anything in their power and abuse their intelligence to get away with their evil doings. Only hard solid evidence will shut them up. Untill then, they play every card avaiable in their filthy stock.
Humans = scum of the earth. All the way filth.
Is an eagle that kills a poor rodent's cute offpsring "scum of the earth, all the way filth" ?
Just like any animal would use all strategies that are in its power to kill his prey/predator in order to survive. Just like any kind of plant rising to reach the sun would do everything it can to kill the nearby plants attempting to rise for the sun too. Sometimes the best strategy is to form an alliance with another living organism -symbiotism- sometimes , most of the time, a life form has to kill another life form to insure its own survival. The plant, just like the lion or the man, didnt choose to be "alive" in the first place. The only options, "choices", "freedom" left to plant, lion or man, woman, kid, are pretty limited, flee, kill, cooperate, die.
"Life", ladies and gentlemen.
This dude could have had contributed to society, his specie, by finding a place in it, an occupation, should have then found a woman to breed with, which is acceptable for everyone else as it is a positive , productive way of life. He could have chose to be unemployed, to have no kids, to be a pain in the ass for everyone too.
But he chose to kill everyone -but himself- instead. Now he's looking for love, attention in return. Daddy! look at me! Look at what you ve done! I'm going to make you pay for what you did to me !
One thing is sure, as world population grow and as it goes increasingly atheist at the same time, there will be more and more people like him.