Mans government system is not fully of Satan as looking back in history i would say that corruption just grows because of feeble weakness, when the tribe of Israel fell it was due to the same corruption as the fire for God went cold and that was the end.It's not about what He gains....it’s about what man will learn from it. The vast majority of human beings will never see how loving God is until they first see how evil Satan is. All of Man's governments/system is of Satan......people still think that they can create a just society if they could only put their man or woman in office....the Nations of the world still thinks that their system is the best. When it blows up in their face they will see for themselves that God is right.
Note that i said tribe ? not that they were Israel indeed, but some people may of been Israel as it fell but most were cold or lukewarm like many of today's so called Christians especially some of the ones that think we are all forgiven for our sins before we were born, pushing to do just noting as a doctrine.