You’re assuming there’s going to be large groups of people that believe money still has value. However, there’s nothing inherently different about the first group of people with guns and the second group of people with guns.
If hypothetically there’s a large moon heading to earth so everyone is going to die, everyone is responding to the same situation.
Less extreme situations result in societal collapse, and that’s just one of many options.
Additionally Lobbying shows us the amount of money for corruption is surprisingly low.