gold gold
spend it on eco
spend it on GM-free game
spend it on special scenarios with you being able to influence pre-set conditions
spend it on HQ and other fancy options
spend it to fight corruption and rebels
spend it on buying possibility to have pink troops and special font in DE
spend it at possibility to be Frontline Pioneer
spend it on tournaments and league games participation
spend it on possibility to get access to map/scenario modding
DO NOT SPEND IT ON MILITARY ACTIONS AS THIS DESTROYS BALANCE
I have no problems whatsoever with GMs as long as it does not change outcome of engagement by 180 degrees.