So long, and thanks for all the fish. 
Or as parents love to say…
“Because I said so.”
[quote=43647:@Paul Sondervan]This one is better.
Hint 2[/quote]
Why didn’t I get it at first? Why?
Oh no, not again!
(…if we knew exactly why the bowl of petunias thought this, we would know a lot more of the nature of the Universe than we do now.)
Maybe. 
If you seriously want to know why, then I think I know. People say normally why, when they see that so much is wrong in life. Thus, they say why, because they don’t find any answer to the problems. But if you think a little bit, you will see that the reason for all that is going wrong in life is in ourselves. It is like writing a computer program. You, yourself, are writing that code, no one else does that. In comparison to this, it is you, yourself again, who plans everything in advance in your life. Some people say “why” because they attribute many things, if not everything, to fate. That is why so many people become atheists. But it’s not God, but you alone that do everything in life, be it good or not. The divinity intervenes only then in your life, if you sincerely and lovingly beg him to do so. He interferes in some mysterious ways for your sake, only if you humble yourself before him.
I know this was a lot off subject, I just wanted to contribute in answering to someone’s crying WHY question, if that person really meant it.
Why ?
@Michel Bujardet I think because of the free will. We have a free willpower. And, unfortunately, we use it sometimes in a bad way.
I asked Siri ‘Why’ and she said:
“I don’t know. Maybe the Genius Bar folks can answer that.”
Do you know what? I did the same thing last night.
I also swore at it (in the interests of research), and it berated me.