I used to play Magic the Gathering more than 20 years ago and even back then, the card that was most talked about was the Black Lotus. There are only about a thousand in print and apart from its rarity, it is also pretty powerful, allowing you to have a head start in battle. It used to go for a couple of thousand back then, which was already considered a crazy price.
Then, I read today that one just sold for $500K in an auction. https://www.polygon.com/23644519/magic-the-gathering-black-lotus-auction-price-2023
Can you imagine if a Splinterlands card sold for that much one day? It is definitely within the realm of possibility.
It's the economy... always has been
https://www.polygon.com/23458064/magic-the-gathering-overprinting-hasbro-stock-downgrade
The above is an interesting article about how Hasbro, which now owns MTG, overprinting new editions of cards. Analysts at Bank of America think they're killing the golden goose, so to speak, which has resulted in resale prices on the secondary market to collapse. Even worse is that overprinting leads to a loss of dedicated fans.
There are lots of lessons to be learnt here for Splinterlands, not least the overprinting dilemma. Ultimately, the question becomes whether the game grows by extracting more value from existing players or by growing the player base. The former is a shorter runway leads to players running to other TCGs of which there are many like Pokemon and Yugi Oh.