mario returned to the coast where it was rich/wealthy bc of the number of merchants that were there and since there was quite a lot of people the people there could afford to pay for his artworks and bc of that mario was able to get commissioned more frequently to make sculptures when giovanni returned to the town he came from that town was mainly focused on farming and giovanni had to farm to be able to support himself financially and that would cause him to finish his artworks at a much slower pace and in that small town no a lot of people could commission him to have him make artworks for them so giovanni couldn't really earn much from his artworks ;c
hope that helps you !! :3