How do mental health issues and the lack of effective intervention contribute to the prevalence of school shootings in the U.S.?

Was life made so hard so that we could learn how to be compassionate toward each other, and not to hold people blame for everything, because we know that life is difficult, and it's inevitable for anyone not to miss things up on it at some point?
Can enlightenment really bring peace and happiness, and if so, how does that work?
Which color would you choose to turn into a physical feeling if you had the power to change how humans perceive the world?