A ban would definitely stop your coinbases and your strikes from buying and selling bitcoin. But your p2p markets...such as your robosats, your bisqs...government would need to get their hands pretty dirty to shut those down ( if they could at all...i doubt it). And p2p wouldnt skip a beat.

robosats, bisq, peach, peer to peer. you cant stop it

It would be similar to acquiring Monero.