I work in support for AWS's security services, which includes both web auth and encryption services. I deal with plenty of IT professionals every single day that don't have a solid grasp on concepts like "don't attach your private key to a support case".

If IT professionals--who are presumably above average in IT knowledge since it's what pays their bills--don't uniformly understand how to handle asymmetric keys, what hope do most non-professionals have?

Do I know the exact profile of what the average computer user is? No, but I'd bet a paycheck that it doesn't include using crypto or private/public keys.