I think its hard to find out which came first, but the moment the government started minting 99% gold coin (and they got away with it) -> 95% gold -> 90% gold till its a worthless "gold" coin too many bad things got put in motion.

I do agree its a confluence of factors. Maybe they expanded too much -> need more money -> print money -> cant exactly fire all the expeditionary forces -> print more money -> squeeze taxes out of populace -> people are getting fed up so output and tax revenues go down -> empire is too big -> attacks on Germany and Europe from the barbarians -> print more money to pay military -> squeeze people - > ad nauseum.

There's an established economic principle that "bad money drives out good". So while I do not think that just printing money is the only cause, once it occurs its down hill. You have to somehow figure out how you will try and reign it all in (thats what they tell themselves at least).

As to the Germany example, the hyper inflation can be fixed though who can really tell how traumatizing and painful it can be to those going through it. For sure it caused some discord and animosity and some people attribute it to the rise of Hitler and so forth.

My point generally is that historians should look at the entirety of factors and weigh them together. It is all too easy to point a quick finger at the military expansion, or climate or whatever and not combine them all. Very few places look at monetary theory probably because its relatively new (really with Friedman's work in middle 20th century), but also because it muddles the simplistic reason.

edit: clarity