Drugs are a consumable, crypto is an item of exchange. If you cannot exchange them, then they have no value.
About 60%+ of market activity is in the USA: https://www.statista.com/statistics/1195753/bitcoin-trading-...
The USA could ban online exchanges in the same way it has banned online gambling.
Sure, trading could still occur via foreign exchanges, but the pool of people willing to put money into the network would shrink dramatically and the price - since the whole thing is a ponzi scheme - would also fall dramatically.
If the price of Bitcoin or Ethereum was 5% of its current value, the levels of electricity and advanced manufactured goods dedicated to mining them would also fall to the same extent.
Turkey (an economic minnow) banning exchanges, and a few tweets from Elon Musk have been enough to send prices tumbling 10-20%. Can you imagine if the USA banned the exchanges?
Its also likely that allied nations eg. European countries, Australia, Korea, Japan, India would follow a USA ban with their own.