The Nature of Treasure and Money

This is more of a general discussion about Treasure in D&D and how it relates to a bunch of human and character activities including crafting and suchlike. 

I do note that D&D by and large treats treasure like candy. Literally, it is like candy and characters are like children. To be fair, this is a very classic way in which heroes and adventurers behave, which is why they're in the predicaments they're usually in, so it is useful to think of it that way. By this, I mean that in D&D, treasure and gold is things OTHERS have or can grant and you adventure to get it. Once you get it, you get GOODIES in the form of magic items or whatever item or thing you desire and that's what money and treasure represents.

This is the perspective in which players themselves might think of money. Many folks are children, so it is natural for them to think this way. Also many folks are average wage earners who also don't usually need to think too much about what money is other than what their wages and bank accounts reflect. Many adults may think of money as a good or a thing that represents a good or value, and that's what money is to them. If that's as far as that goes, then yes, that's fine.

What money actually represents is power. Actual, real power in the realest of the senses. It is kingship. It's merchants. It's the ability to raise an army and establish a stronghold. It is the ability to tell people to do what you want them to do, and then they do it. In this sense, money is limited both by whether or not people are susceptible to be influenced in this way, but also by the relative amounts of power other people have. That is, not only does a small village lack the gold liquidity to purchase a ton of things, they also wouldn't be particularly interested in 700 swords because none of them really need that. They're not merchants who can sell the swords you're selling, and they're not dukes who might need it to outfit an army.

A player who is asking after how much money their character can make during downtime by crafting things is operating on the candy level. They're not seeing money for what it actually is, and if you're not creating a world beyond a candystore, more gold can seem more and more useless the more a character gets insane amounts of it. Once you've bought everything in the candy store that you want, the money becomes useless.

The real answer to the player's question, of course, is that they're trying to make money by practicing a profession. Whether they want to make things, or perform services for people, or what-have-you, they're trying to extract purchasing power from society by bartering the skills and capabilities their character's possess. The rules for that isn't covered by the crafting rules - those are for creating personal items the PCs will use. For making money, you use Downtime Activities - practicing a profession. You get 1 gp per day normally by practicing a profession. Belonging to an organization such as a Wizard Circle, Thieves' Guild, Weaver's Guild, or temple get you 2 gp per day because you are borrowing the organization's power and influence to get more for the same labor. NOT belonging to them is conversely very bad because guilds are historically very jealous about the practice of professions and you simply can't be making as much money as the nearest guild member or they're going to ask their guild to shut you down.

By the time they're 5-10th level, I think DMs should be introducing the idea that PCs are starting to significantly alter things in their society not only using their personalities and face to face personal influence, but also simply by virtue of how they spend and make their money. In this sense, 3000 gold pieces doesn't merely represent buying power they can use to purchase personal magic items, but the ability to commission a boat that can alter the economy of a small seaside village. This is particularly appropriate if you're using Bastion Rules because a bunch of 5th level adventurers who have Bastions and Followers are creating and offering services that would not always be available in villages, and wouldn't be numerous even in small towns. Your Fighter's Barracks could represent the only significant private armed force in a small town that isn't part of the local constabulary and you can bet your ass the Mayor is going to be talking to you about it. Your 12 Barracks Defenders is a bonafide Infantry Squad which is a legitimately basic army-sized unit of force.

I understand that this can be scary to DMs, but the purchasing activities of a party of 8th level characters SHOULD change your world map. 3rd level adventurers open their purses at the Magic Shop salivating over goodies. 8th level adventurers store their wealth in banks and guilds and they think about what they should be purchasing by looking at the world map.

Realism, in the world of Summoning Dinosaurs & Custard Damage, is fairly nonexistent.

But I get what you're alluding to.