What is stopping the US Government from outright BANNING Bitcoin?  For argument's sake lets say today (23JAN2020) 3% of the US population is using Bitcoin for 3% of their purchases or financial transfers/transactions. And, let's say 5 years from now around 2025, 30% of the US population is using Bitcoin for 30% of their purchases and financial transfers/transactions.  Consequently, the US Government monitoring this situation sees the trend that 30% fewer transactions are being done with the all mighty US Dollar. Well, it would seem that the US Gov would hold the view that the popularity or use of their US currency is being threatened by Bitcoin. And so, what is stopping or what would stop the US Gov to outright make it ILLEGAL to use Bitcoin at some such time?