BTC seems to be about 10 times more volatile than the dollar on a daily basis. Like, last friday, the dollar was down about 0.4% and BTC was up or down 4-5% intraday.
This seems to me kind of like the argument that the government is "just" another gang of armed bandits.
There is a huge amount of value in predictable taxation rather than random robbery. Partly because of the variance, and partly because government has more of a long term interest in the viability of the citizenry, even if it weren't especially democratic per se.
And similarly, there's a huge value in a currency that gradually loses value over time rather than being up or down 5% in a day and 30% in a few weeks.
The whole point of currency is that it's not a long term investment asset, but a tool for trade, isn't it? So why would long run inflation be relevant?