If the US government came out with legislation strongly in support of bitcoin, they trade for the upside just as easily.
And there's much more money to be made on the upside than the downside. And it's probably much safer to make the upside bet, because a) the PoS market is very dilute and contested, so there's no clear winner to bet on unlike the PoW market and b) you can ban bitcoin or PoW in the US, but the US can't control how other parts of the world treat it, which means you don't know exactly how the globally driven price of bitcoin is going to go based on the actions of the US alone. Down for sure, but not all the way to zero.
Hell, we can see what happened when China banned PoW mining. Price went down temporarily, and then it roared back up.