I've toyed around with the ideas of having the PCs belong to the Baker's Guild and adventuring in order to protect their trade. "If the dragon eats enough of the population we won't sell as much bread!"
Which would make sense if the PC's were Ferengi, but probably doesn't simulate most of humanity very well. I could be interesting to have a species like Ferengi that came at the problem of ethics in a backwards manner like that and whose compassion was predicated on understanding people as potential customers, but I don't feel most players are going to conceive of their characters in those terms.
Economics to me work less well as primary motivations than they do as simulating the struggle of achieving your primary motivation that we are all familiar with from life. Why do you keep track of ammunition and how many days of rations you have? Why is it interesting if things start falling a part if you've been trekking through a steaming jungle for two months? Because in real life, that's the struggle we all relate to much more than we relate to killing the dragon.
Things feel more satisfying when they feel earned. "Here is all the wealth you'll ever need, and you didn't have to work for it", isn't very satisfying. You can do whatever you want, and there isn't a stuggle to keep it working, isn't that satisfying. "We're turning a profit!" can be a really cool point in an RPG, where you start to slowly build your way up. How many computer games are there where "the struggle is real" is actually the core loop of gameplay that keeps you coming back so that you can afford that next widget or upgrade in your universe of quality of life enhancements? I think you can do that in an RPG, and certainly D&D has traditionally done that with dungeoneering supplies in the form of magical items - the old random treasure tables almost had a 'loot box' quality to them where you were hunting for the rare drops. But I also find that if you make the non-combat aspects of the game somewhat tangible, that you can do that with with all sorts of areas - I need just a slightly better army, I need just a bit better castle, I need just a bit more income to afford that castle, I need to upgrade the cities cathedral, I need to enduce more immigration, I need that NPC to like me, I need a library upgrade, etc. etc. etc. The more subsystems and minigames you have to play if you want to play them, the more you can have going on. You don't have to play all of them, and many groups won't want to, but they can be fun and in particular they can be an awesome change of pace from just playing dungeon minigames and combat minigames over and over.
