Bit coin has no intrinsic value. It's only valuable right now because people are willing to pay fiat for it. If fiat goes to 0, so will bit coin.
So, if fiat collapses, then what will be used to pay for a gun? According to you, it couldn't be gold or silver because they are only valuable right now because people are willing to pay fiat for them.
Also, the Venezuelan bolívar has basically gone to 0, but the value of Bitcoin in Venezuela has not gone to 0. So, how do you know that if fiat goes to 0, so will bitcoin?