First of all, I make money of grinding, by selling the drops I get, usually the disjointable items monsters drop, those make you a crap ton, especially if you got a looting pet, I made about 200k from disjointable items within 3 days, Fast money much?
and its a pain in the butt disjointing them with the stupid rondo's, and its difficult convincing people to buy elements because Magic/Attribute stones work like elixirs, not often
Other people do Trade Runs for money, you can make a $#!TLoad off Trading if you can survive the 1* Poppers

and the NPC thieves and other monsters on the way, I spend like 40k on prep, make 55k on the end of the trade <3
But its proven that grinding CAN make more profit off grinding because if your 1* popped then you spent prep money on nothing