No. Declaring a commodity to be illegal is not a fast, cheap, or efficient way to destroy it.
See, e.g., Prohibition. Or Prohibition 2.0: The War on Drugs.
Exactly - but drugs can be made, and manufactured.. Bitcoins cannot, there is a finite limit. Of course people may eventually move-on to other crypto-currencies, but the u.s. could buy up all those super cheap as they come available as well.