I always wonder the same about people who are ill.
I asked about whether or not going barefoot would cause my arches to "fall" and I think it was MamaGrok who said that our arches are muscles and naturally built to be worked. She equated them to bridge arches and how they're strong structurally and don't fall and don't need anything to hold them up. I wonder if it's a situation where you wear shoes with arch supports so your arches don't get the "workout" they need to remain strong and when you go without arch supports they "fall". What she said made sense to me and I'm not going to question it. I have a medium arch and was told in the Army to make sure my arch doesn't "fall" (what the hell does that mean anyway??) and so far after 2 months in my fast flats I haven't had any issues in my arches. everything feels great.