In the event of a societal collapse so great that no money is usable, it's pretty hard to imagine people caring about Bitcoin. There might not even be power in this weird Mad Max scenario. They'd probably want to barter for goods.
Societal collapse doesn't have to mean going back to the stone age, it could mean e.g. the Iranian revolution. Or for a contemporary example: the Syrian civil war.
Even Spain was a dictatorship until 1975. Everybody should consider the possibility that their society will collapse, even if they choose to do nothing about it.
My point is that there are a lot of things that seem like they'd be better to have in case of societal collapse than an Internet currency with no intrinsic value that you'd have to educate most of your (possibly former) compatriots about just to have a chance of them letting you use it.
I can't give any such example. However, EVERY economic collapse has been followed by rebuilding. Maybe the nation has a new name or new boundaries, but something is always rebuilt. And once it is, gold has value again.
I hear Bitcoin is popular in Venezuela, where the people hunt pigeons for food after the communists took over. It's also popular in China, where - again - people are scared of their government.
I don't know that the US federal government is as scary, but it's not unheard of.
Oppressive governments are essentially the only good reason to use bitcoin, since the usual financial system is far more efficient at storing and transmitting money. He's either evading taxes or speculating.
My bank charges $40 + 2% forex spread for a wire transfer to Thailand. With Bitcoin I actually come out at a small profit. Bitcoin is way better at consumer level international transfers than banks.
Even generally non-oppressive governments make errors, and it happens more often that you'd think (and suing might be prohibitively expensive, untimely, or not an option at all).
The usual financial system is far more efficient at converting your wealth for the use of the oligarchs. USD for example has lost almost 100% of its value since the institution of the Federal Reserve system. The wealth did not go away. It was merely transferred from the populace to the rentiers.
So you think when society around you is failing you'll still have enough infrastructure to be able to do transactions in bitcoin? Seems like a narrow scenario. Bad enough that there are no reasonably stable fiat currencies to be able to trade (whatever they may be because my value is in companies not currency so I can use whichever) and yet good enough there is still a working internet and enough miners for the blockchain to work.