Anyone who is even remotely involved in precious metals knows that Fort Knox is the center of one of the biggest goldbug conspiracy theories. The story is that Fort Knox doesn't have as much gold as they are purported to have, which means that total US gold stores are less than they say they are, which means physical gold is worth much, much more than it currently is. It's the Holy Grail of gold conspiracy theories and the fact that Trump is going to audit Fort Knox is actually really hilarious.
At this point I won't be surprised if he declassifies all of the UFO/UAP files.