Once upon a time, in a different game system, my character stumbled upon a way to get wealthy, obscenely wealthy, by becoming a merchant in rare and exotic goods. The keystone was realizing that one could hire "adventurers" to seek and recover goods for far less than one could purchase them from other merchants or collectors. For the truly interesting and difficult, this merchant would "hire" his acquaintances and himself.
The group didn't figure it out for almost two years of play; not till the thief decided this Really Rich Merchant would be a good target for his new scheme and brought his friends in to help.