Why is the usage of forking?
Trying to manipulate the market due to self greed, in an attempt to squeeze out more Bitcoin from others.
This response couldn't be further from the truth. The reason for a hard fork is an attempt to propose an improvement to the Bitcoin (and its blockchain). A success would lead to a better "bitcoin" and a failure proves that the a majority of bitcoin miners believe that is good as it is.
does forking give any advantage to the users?
No. All it does is create confusion and possibly damage if there is no replay protection. Roger Ver, Jihad Wu and co. are mostly responsible for those.
No. It could offer a benifit, that's why a fork is proposed. Roger Ver hasn't had influence in all forks, so stopping talking shit!