Why should decentralization be trusted?

We've been using money for hundreds if not thousands of years of now. You have a trusted third party (often a centralized bank), which prints and gives currency to people.

When you take this process away from a centralized entity like a bank and decentralize it, it appears very very chaotic and anarchist.

So, how can this whole process be trusted? The amount of money printed by a country is proportional to the amount of gold a country has, similarly digital currency is also capped at some amount, there are only x amount of total bitcoins, for instance. Fair enough, but wouldn't this mean anyone can start creating digital currency? I find the whole idea very very unstable.