This is actually a good signal to start buying again, when nobody wants them. I have a few theories why cards from the 50s and 60s became so sought after. It’s essentially a supply and demand issue. People in the 50s and 60s collected cards as kids, not as investments, but just for fun. They grew up, moved out, and their parents threw away all their cards. They became scarce and subsequently, very valuable.
People caught on to this in the 80s and 90s, but then thought of them as “investments”. They didn’t get thrown out, or not in appreciable amounts. These cards aren’t as valuable as a result.
If cards are unpopular now, this makes a set up where companies maybe won’t produce as many or people won’t save them. We may have another set up where people don’t care about them and the supply:demand ratio in the future may again be very low. We’ll see!