For those considering running an economy, I support them very much.
Also, a Fizban Dragon hoard can easily reach 300,000 gp in currency, not equivalent gem value. Since there is 50 gp to a pound, that's 6,000 pounds of gold. That's roughly 3 tons of gold. Interesting, the amount of gold that was mined in South America between 1500 and 1800, causing a great economical upheaval in Europe, is estimated at 180 tons. That's, roughly, 0.6 ton per year, distributed over a much larger economy than the medieval-sounding assumed default setting. Mansa Musa made his hajj carrying 18 tons of gold to cover his expanses. His pilgrimage imbalanced the economies of Egypt and Africa for a generation.
I have a villain whose goal is to corner the silver market. He's buying silver over the 10-to-1 conversion rate. He's bleeding gold because he's casting a spell to inoculate a disease on gold pieces that will make them rust, losing value over time, so silver will become the only standard in which people will trust. He can afford the leading losses for enough time for his contaminated coins to reach the kingdom's treasuries and infect them... I don't know if this will ever become an adventure for my players to investigate, or just a part of lore they might encounter, but I really like economies in game.