What do you have to tell him a DM about gold? Also, gold is not the only "real" money. There are reasons why gold back currencies are good but fiat currencies also have a positive impact. The issue with the USD is not that it is a fiat currency. The problem is that it is abused causing inflation, which is a tax on holding the currency. Its not good to hold USD because the high inflation makes it costly to hold.
In contrast Gold is deflationary. However, lots of currencies are deflationary and you can hold lots of things that will not reduce in value like USD will. Owning anything that doesn't lose value over time is better than holding USD.