I'll tell you who else was buying the metals like crazy, this last month in particular...
Institutional investors who tried to short the metals on their way up too early. They got fried alive and kept burning on the way up. I suspect that many, many of these investors were unwittingly pushing the prices higher as they were covering their losing short positions leading into options expiration...a classic short squeeze with options expiration week as the catalyst.
They all shorted too soon and burned each other up.
That "demand" for the metals won't be there in the weeks ahead.