So my thinking is that if they control supply (they do of course), they control demand, and that there is no “per-card” demand curve. If a card is reprinted and drops from $100 to $50, they can reprint until it’s $10
I think you do not understand what a demand curve is and should look up some econ 101.
The demand curve is how many of a given card customers (in aggregate) would buy at a given price.
Wizards could reprint any card into the ground if they wanted to (which would be far below $10), but that would likely not be the strategy that generated them the most profit, and there's no actual reason to think $10 is the price point that would do so either.
Asking someone to look up Econ 101 isn't necessary to make your point.. You probably knew what I meant. You probably knew that my point is they control the supply, so they control the price- the equilibrium price if you like.
The demand curve is how many of a given card customers (in aggregate) would buy at a given price.
Wizards could reprint any card into the ground if they wanted to (which would be far below $10), but that would likely not be the strategy that generated them the most profit, and there's no actual reason to think $10 is the price point that would do so either.