"I don't know why the laws of physics exist. I don't know why the universe exists."
Stop there and ask yourself: "If I don't know this, how can I claim to 'know' anything?"
You "know" the consequences of certain laws, yet you have not observed life coming forth from simple compounds. How do you "know" what you say it true then?
"How do you "know" what you say it true then?"
I don't know. It is my best hypothesis given what I have seen and studied on this planet. If you have a better explanation than mine I would love to hear it.