Monero could lose it's purchasing power at approximately the same rate as Fiat, I would still use it.

It's the most reliable private way to transact online.
Yes, you could use Z-Cash, and Mixers, payjoins, coinjoins, etc. too but Monero has the highest anonymity pool, and is more convenient to use, guaranteeing stronger privacy for the general population.

That being said Monero hasn't, by most metrics it's been one of the best performed just as good, if not better than Bitcoin recently.




Some additional links to look at.
https://bitinfocharts.com/monero/

https://www.cryptocurrencychart.com/top-return-on-investment/week

https://tradingeconomics.com/btcxmr:cur

https://portfolioslab.com/tools/stock-comparison/XMR-USD/BTC-USD