You can use non-USD currencies to judge how the US stock market has fared to avoid the issues with currency health. You may argue that dollar-denominated returns aren't real, but SPY isn't down even when denominated in EUR https://ycharts.com/indices/%5ESPXEUR

>median wealth (currently below 2007 levels in the USA)

This is outdated -- it surpassed 2007 levels in 2022. https://www.federalreserve.gov/econres/scf/dataviz/scf/table...

> SPY isn't down even when denominated in EUR

*SPX and no, it's down 2% when denominated in Euros while up 15% when denominated in dollars. I wouldn't say the USD has fared well so far.