That's a good point. I think the "mostly" is highly dependent on the rate of "money printing" and where exactly this money goes. But the Libra/Fiat rate might not be necessary anymore as an indicator once it becomes a useful indicator because of rising consumer good prices.
> BTC does not provide price stability.
If bitcoin gets adopted more widely and has a bigger market cap the volatility should go down. The supply shocks every ~4y due to the block reward halving are getting smaller too. But sure, a free market money will never be as stable as a currency with central bank interference. For me that's not a bug but a feature, it doesn't shield market participants from economic realities, so they can actually adapt.
Btw, free market currencies can be much more stable than central bank currencies. See eg https://www.alt-m.org/2015/07/29/there-was-no-place-like-can...
But that's affected mostly by factors other than money supply?
> all big fiat currencies aren't stable enough even gold or BTC
BTC does not provide price stability. Hardly anyone quotes long term fixed prices in BTC, they quote them in USD/BTC spot converted prices. You can see this in how BTC has tracked up and down against the dollar across a huge range.