The ever-popular Pokemon franchise took the United States by storm in the 1990s and continues to be one of the most profitable franchises in the world, obtaining just under $100 billion in estimated total revenue since its inception in 1996
This identity has been a consistent element through its various appearances, whether it be in the anime or different gaming platforms, making it a staple character in the Pokmon franchise
Riverchurn Monument is the kind of mill card that scares me, because it tends to combo with a bunch of mill favorites like Bruvac, Phenax, God of Deception, and ways to make players mill a lot of cards (Maddening Cacophony, anyone?)
Seeing heavy play in Standard, the Elder Dragon enters with a Treasure token, with the option of casting Instant/Sorceries off your artifacts
Different platforms take a different cut of the profits (10% from TCGPlayer, 10-15% from eBay) and you'll find cards are more or less likely to sell on different marketplaces