I've lost track of how many SD cards I've lost now. No one I talk to seems to have these issues.
Today I lost another one, this one because it was physically broken, that is, the whole front corner of the card was broken off, so it no longer hits the little spring that indicates there's a card present. That's now two physical issues (another card had the top and bottom of the card split apart), and lots and lots of corrupt SD cards, due to purchasing almost-but-not-quite supported SD cards (right manufacturer, but ordered the wrong sizes because I thought "oh, I can double capacity for just a bit more money"), and one card that just seemed DOA (supported in theory, just not readably by *anything*).
Now I'm back to a working machine, but only if I unplug the external (powered) hard-disk momentarily during boot. Once it gets past post I can plug in the HDD (which is what the system actually runs from), but there seems to be gremlins baked into these pis.