Cos people can't see the fog above their high horse. the ones that feel cos they went through the lands of the ice and snow with the midnight sun and where the hot springs flow to earn their gil in game...so because they did you have to do the same also...because...heck if I know lol
At the end of the day nobody knows but you and nobody cares either because other players don't know. How do you tell the difference between if the moneys you got in game came from in game or if a player tossed a $20 on cash shop? It really doesn't matter, Player X gets their gil, Player Y sells the item they wanted to sell and gets payed, the company gets a couple dollars more. Everyone is happy all around.
Well maybe not the ice and snow people.