The USA is no longer on the gold standard, and it is debatable as to how much gold the government actually has
They shifted from gold and silver to black gold AKA oil
They eventually decided to dump a bunch of silver onto the open market which drove the prices down.
That wasn't a smart move... unless they really needed the money they should have sold throughout a longer time...
The US government can get all the money it wants, so I don't think profit was the goal.