Celebrim
Legend
I think adventurers are indeed eventually going to enter the realm of the wealthy...
There is one hugely important thing to understand when looking at the default D&D economy and that is that back in 1e AD&D, Gygax created not one but two economic systems. The first economic system was the "Adventurer Economic System" and it was primarily used to price treasure pulled from dungeons and expenses that Adventurers were likely to incur. Using modern parlance, the system was explicitly "gamist" in its purpose in that it priced treasure based on the idea that in a fantasy you should be finding large hordes of gold coins, and it priced expenses based on what Gygax perceived as balanced game play. The standard coin of this economic system was the gold piece.
At the same time, Gygax created a second economic system based of his knowledge and understanding of real world historical economies. This system was used to model the ordinary NPC's in the universe that made up the flavorful backdrop of the adventuring world, and was also used to value the amount of wealth that players could pull from the economy through non-adventuring means. The main purpose of this system was "simulationist" in modern parlance, although there existed for it also a "gamist" purpose of deterring groups from abandoning the core intended gameplay of going down into dungeons and kicking the doors down. The standard coin of this NPC economic system was the silver piece, and consequently it was only 1/20th of the size of the PC economy.
I'm not experienced with 5e, but as soon as someone said that the standard wage of an NPC in 5e was 2 silver pieces, I started expecting that like past editions before it, it has artifacts of Gygax's original two system division. And anyone that is planning on looking at realistic economics for their campaign has to immediately recognize the unreality of the two separate economic systems, the troubles that can come when those two systems intersect, and figure out how to reform the game so that both PCs and NPCs are using a single system.
In particular, the two systems are intersecting on the subject of bribery. If the NPC is accepting bribes scaled to the NPC economy, but the PC's have bribing power based PC economy, then the PC's will have 10-20 times the wealth of the NPC's and as a consequence bribing susceptible officials will have trivial cost.