It would be insanely easy for the US Government to shut down bitcoin, if they wanted to. All they would have to do is make bitcoin illegal and have ISPs block bitcoin P2P traffic. They could also shut down the exchanges and prosecute people who were found to be attempting to buy or sell stuff with it.
Bitcoin's value would plummet to almost nothing, virtually overnight.
The ONLY reason bitcoin exists is because the government LETS it.
Before the Civil War, thousands of businesses, local governments, and private banks issued paper currency in the US. This enabled all sorts of scams (banks that didn't exist or wouldn't pay full value, etc.) The federal government was barely a player in the space, with sporadic and limited issues until 1861.
With the National Banking Act in the 1860s, the federal government slapped a 10% tax on privately issued notes. The industry collapsed virtually overnight, federal government notes take over the ecosystem, and we start to see a currency ecosystem which resembles the dollar we know today.
If crypto becomes a serious logistical problem for state actors, we'll see the equivalent trick. Spinning up a state-backed digital coin is a relatively modest technical task, because it doesn't have to solve the decentralized/trustless problem. Just take existing banking infrastructure and scale it horizontally. Any s such state-backed currency just has to be cheaper than (your favourite crypto) + (penalty taxes) to immediately win the mainstream market.
This model also puts a significant direct motive into deanonymizing privatecoins. The revenuers may not care you're using XMR to buy fentanyl, but once they can demand a 10% cut of it, they care about who owns them.
The goverment SHOULD tax Bitcoin as a property, then it would be an incentive for Goverments to keep its value high and everybody wins.
States can create their own digital currencies, but as long as they can create an unlimmited ammount of it, then your savings in that currency will loose purchasing power, and it would be no different to the system we currently have.
Bitcoin is a savings technology, you can also have other assets as real state, gold. I don't see the Goverment excessively taxing those other assets. Bitcoin should be and will be taxed similarly to those.
There is the constitution and I’m not sure everything you said is constitutionally legal. The government could pass a law saying I need to slap myself in the face every morning, doesn’t mean it’s constitutionally allowed.
Sure, they can prosecute everyone holding Bitcoin. It would be as effective as the war on drugs.
They can shut down the exchanges, block ISP traffic but only in their jurisdiction. They cant't stop Bitcoin mining in every other country. They can't stop people from Africa doing business with Bitcoin. Or people in Venezuela where you see an real use case for this technology.
The network will continue to grow without US if they choose that path.
Or US Goverment realizes that Bitcoin might be the tool they need to revitalise the economy, and to avoid loosing influence and allowing China to continue growing stronger.
Bitcoin's value would plummet to almost nothing, virtually overnight.
The ONLY reason bitcoin exists is because the government LETS it.