For an SD card, “store something you care about” will very often mean photos or video. You have no choice but to trust the SD card for the time it takes you to get to your computer where you can dump the contents into something more reliable.
High end cameras usually have dual card slots to help deal with this, but even that won’t help when the failure mode is trying to write past the cards’ actual physical capacity, because the counterfeit advertise more storage than what’s actually there.
“Care about” could even just mean wanting the thing to provide at least, say, two nines of reliability. If my Raspberry Pi stops working after 2 years because the SD card failed, fine. If it stops working after 1 day because the SD card falsifies its capacity, I have zero nines and I’m not happy.
It just generally works poorly without large amounts of luck. Lots of counterfeit or garbage goods will work okay at first but wear out quickly or just be dangerous to operate due to cheap parts.