Bitcoin could only be defeated if every node everywhere was taken offline and every ISP everywhere was forced to block communication with the network.
Not gonna happen.
And the value of Bitcoin is not in terms of fiat currency. It's in terms of how it can be used to fuel an economy that is still in development.
Eventually digital services will run absolutely every aspect of day to day life. Cryptos are the only really economically rational solution to easy, seamless, fast and efficient transfer of value between consumer and producer in a digital economy.
Short term thinking fuels fear.