deskthority

Just wondering people like Mito/Matt30, do they earn from what they do? Or do they just play the part of designing and it was the vendors/producers(GMK/SP) who earns after the group buy concluded?

Yes and no. There are GBs where the designers get a kickback of money, some where they just get a copy of the set, and some where they get nothing at all. I think it is safe to say that Mito does make money on his sets.