Targeted buyouts like this can be annoying, but not unexpected. The truth is, though, that Nykthos is about to rotate out of Standard in October. While certainly playable in Modern (it does see play with Elves, for example) it’s not unlikely that a new supply of Standard-only players will be dumping their copies into the market. As it is, Nykthos is always going to be popular among casual players and it’s a must have for monocolored Commander decks. This is definitely one of the best foils to have around.
I probably wouldn’t buy at this super high price as it should stabilize. The $72 TCGPlayer median price is misleading, as that’s actually the high. It’s perfectly possible to still find copies around $20-30, and if you can pick up any at the lower end, they’re a perfectly good long-term investment.