Fiat needs coercion/violence to survive.

Every fiat currency has laws that basically make it such that people have to use it—or else.

Besides Income Tax (in Australia) I’m not aware of any laws that force me to use AUD. If I decide to stop working one day (and get rid of all my investments) and live 100% off-grid – I would have to continue to pay my rates (land tax), but that’s about it. I could in theory just go back to a bartering system with my neighbors or local community and live that way. So i’d be living 99.8% without a fiat currency.

It’s all taxation. Don’t pay your taxes? They take your stuff, lock you in a cage, and/or shoot you. If your store your value in anything other than AUD and it appreciates, you owe income tax on it at some point. This is typically when you “realize the gain”. Although, I have heard (never confirmed) that some countries tax unrealized gains in some circumstances.