An economists main role is to gain money. The best way to do this is to have a high level and high max energy. You spend most of your ap on max energy as you level and fight using 500 energy on each battle against mythical creatures than you can safely beat. You train only your strength as this dictates how strong a creature you can tackle. The higher your level, the more energy and more credits you get from a single graveyard train. You can also support more mines at a higher level and this is an added source of revenue.