> So basically, the way I understand it, money is just a means of getting people to do work.
More like get (or enable) people to trade with one another.
> So the ceiling is much higher, but there's still a ceiling - go too high and your currency is in trouble.
I think this is the problem with MMT as it doesn't give an answer to what should you use to store wealth. Money should not be used to store wealth (that's not its goal) but to make a transaction possible between two counter-parties.
> Can it ever recover if people lose trust in it? Since that's a major part of what's keeping such a system going.
You shouldn't really care. Think if we can develop a system where one could work and exchange value in one currency, and store value in another currency. The first currency should disappear as soon as the transaction ends, and should appear as soon as there is a need to transact. The second currency gives a society IOU to give you a transaction in the first currency in the future.
Not sure how to do it, really.