Nobody thinks bitcoin is backed by gold, but I would wager that many people (maybe most people?) believe that the U.S. dollar is.
Seriously?
I think 99.5% of people simply don't give a damn.
They get paid in dollars, they can pay all their bills and buy all their stuff in dollars. They don't care what a dollar 'is'.
People who actually care about a gold standard are about as common as people who build survival shelters on their land, just in case.