These are the hardest questions that scholars and saints have been grappling with for millennia. Sikhs have been doing the same from the beginning of Sikhi, I suppose, except maybe for the Gurus themselves who do know the answer.
For my own sanity, I must believe that all is Hukam of Waheguru. My only explanation of these evils is that we are very small creatures of severely limited vision; perhaps if we could see the Grand Design as a whole and examine how it all fits together, we could comprehend it.
I know from experience that we can grow strong from painful occurrences in our lives. As Nietzsche said, "What does not kill me makes me stronger.."[Was mich nicht umbringt macht mich stärker.] (I give the original German because this sentence is usually mistranslated. )
I know that's a lousy answer, but it's the best I can do.
That's called perspective.
And that's what were meant to learn. To see God in everything.
What we sow is what we reap. Some can't accept it, but it's the Truth.
I've been through hell and back, and even I accept that's its all been him.
Instead of hurting others I have learned to be kind and compassionate towards others, instead of being arrogant, I've learned to put my head down on the floor and to accept that it's all Him, good and bad, wealth and poverty, light and dark, success and failure.
Ive also learned from the fools mistakes. Fools are there to show us what we shouldn't be.