Well, it's convertible to cash/gold so long as it maintains a "believe-in-it value". How intrinsic is that?
Fiat currencies (namely the USD) are intangible by definition -- not freely convertible into gold... they are no less or more so convertible to gold that BTC. I actually sold some BTC last week and bot some gold with the proceeds.
Yeah, the USD is more stable by historical standards. The DM in the 20s didn't fare so well. Argentina, etc. The argument vis a vis one Fiat vs. another is moot. None of them are convertible by law. Stating that the USD won't drop to zero is a valuation argument. The govt guarantee isn't worth shit.
The DM deval was far more pronounced (lol) than the gains in BTC to date: