Tell that to the guys who purchsed Bitcoin when the exchange rate was going at $1,200 per coin. Bitcoin has lost 80% of its value, from its peak, which was reached in December 2013. No fiat currency has suffered such a crash. The worst performing fiat currency is the Ukrainian Hryvnia, which has seen its value dropping by 60%.
*ahem* Deutchmark under the Weimar republic. Venezuelan dollar in 2005. Zimbabwean dollar around the same time... I can come up with others. Where BTC did better, is that it did bounce back.
I was talking about the situation since 2013. Out of the 200 or so different fiat currencies (plus BTC) in existence, Bitcoin is the worst performing currency against the US Dollar since December 2013. Historically, currencies such as the Deutchmark and the Venezuelan dollar have suffered even worse crashes. But they occurred years, if not decades ago.