Everyday thousands of illicit transactions are carried out on the blockchain. The US government has never shown a shortage of force when it comes to stopping drug dealers. Yet the number of people who've been arrested based on blockchain analysis can be counted on one hand.
Once you start getting into the tens of thousands of USD, you can afford to obtain bank accounts outside of the country tied to a business. These are widely available and there's an entire cottage industry of lawyers who can provide everything you need.
Thinking that there would be a network when even the slightest disruption to civilization happens is simply naïve. The internet would probably be the first thing to go. Even before electric cars.
You also don't need electricity (or most other modern luxury) to modify, trade, or use gold -- plenty of gold changing hands throughout the ages.
Cryptographic currencies have their use, but if the economy is looking shaky I'd rather have cash, gold, silver, cans of beans, or ammunition; BTC wouldn't even rank top 25.
Get the fuck out of here.
I wouldn't say "GTFO" quite yet. Not without some more explanation for why you think it's so improbable.
I really doubt that anyone is buying bitcoin for the collapse of industrial civilization. The more prepper-case for bitcoin comes from either very high inflation, financial instability, and/or severe capital controls. It's not implausible that these conditions coexist with the continued existence of industrial civilization.
It's not implausible because it's happened many times before in history. For example, if you were a Jew in Germany circa 1936, Bitcoin would have been very very valuable to you. In much the same that diamonds were valuable to those in that time and place, because of the ease by which they could be hidden and smuggled against the authorities' wishes.