Who benefits from mining? After reading many articles, I didn't find an answer to the following. 


  "Miners use special software to solve math problems" 


Okay, but for whom? Are there organizations or people that need those math problems to be solved?
Its not a math problem. Its just search for partial collision in function called sha256.

Sha256 is a famous type of puzzle.

During the writing of this post, a block  397108 was mined.

The solution looks like this:
00000000000000000497b28e9c38673ef8fd2fed317d6eca8a579350b1cba0a6

Notice the zeroes on the beginning. The more zeroes the harder is to find a solution.

The only reason is to waste power to prevent creation of funds from thin air (prevent print too much money) and to confirm payments.