No, banning fiat on-ramps will not kill Bitcoin, although it would suppress the price for several years. No, banning exchanges will no longer work as trading would move to DeFi. Give it up already, your arguments are tired.

I don't think you realize how strong the crypto movement is. Your vision is obscured by all the the snake-oil surrounding it. Government intervention will further legitimize it. This is nothing like the prior movements for alternative currency. Many millions of young people have experience buying and trading cryptocurrency now. It isn't going away.