Mainly because some are valuable enough that you should declare them on your insurance
Here's an example of an unexciting Hellbent card printed more recently, in Modern Horizons 2 : Necromancer's Familiar
Since youre in green and white, you have access to all sorts of protection spells like Heroic Intervention and Teferis Protection, letting you keep your commander nice and safe while you disrupt your opponents plans
They have also been found in Best Buy, Hobby Lobby, Michaels, Kohl's, TJ Maxx, Five Below, Party City, Burlington, and Big Lots, as well as in smaller stores like Walgreens, CVS, Rite Aid, Hot Topic, and Gamestop
Websites like eBay , TCGPlayer , and auction houses track prices for verified authentic cards