The problem with socialism is that you eventually run out of other people's money.
There has to be something to buy with that money or it's worthless paper and metal. There have to be people working to provide goods and services. If that's not the case for whatever reason--because of a lack of resources, because enough of society has broken down that people can't, won't or don't work, or whatever else--you see failures.
So it's not just a currency problem. It's a problem of whether things that are actually useful to people are being produced and money is just a way of measuring the exchanges. Pretty much any naive maximization of money results in issues, whether that involves ignoring externalities for profit, or broken incentives caused by distributing piles of money that cannot, on average, be exchanged for useful goods or services.