why laws of nature really exist?

Answer 1

As far as I know, we don't know WHY they exist. We have enough to do to find out what these laws are.

From a religious point of view, you might say it is God's will.

Answer 2

Here is a little more to think about.

http://drdavespsychologypage.intuitwebsites.com/Proving_a_Point.pdf