We still send them - though fewer each year, what with people dying off, plus I stopped sending to a few very far-flung people we haven’t seen for years and almost certainly never will again.
I like receiving them - they form part of our decorations, blu-tacked to a few vertical surfaces.
I’m quite sure that the two couples I know well who stopped sending cards a few years ago, didn’t stop because of the cost - they’re all very comfortably off - but because they just couldn’t be bothered to write them any more. Which is fair enough, but it might be nice if they just admitted it, instead of turning it into a virtue-signalling statement about saving the planet and (one couple anyway) donating the money to charity, instead.