I could be misunderstanding this, but you know that you can buy ETFs that are currency hedged?

Taking Vanguard for example, VGS is global equities, but VGAD is global equities that are AUD-hedged (my home country).

The only downside is that you pay more in fees (and they're less tax efficient). People generally don't bother with it though, because on a long enough time-line currencies usually revert to their long-term average, so if you're holding for retirement there's generally little point.

There is no 'cure' per se as a non-US investor currency risk is just something to accept (or swap return for a hedge but then it ends up being a wash mostly), for example if you invest in a World equities ETF, it's a bit pointless to be hedging exposure to all the currencies. Even if you decide to slant away from the US, it's likely a majority of non-US large caps have USD exposures.

It's more a psychological thing, you see absolute USD return and think you could've made that but there's not the actual return, your actual return is post conversion, if you'd have hedged you wouldn't have that abosulte return either, so you've never had it.

Additionally, if you're like most people and investing regularly or DCA-ing from now on you can buy at lower USD

Everyone wants to park some money and have other people work hard to increase the real value of said parked money. Not everyone can win big. Storing value is actually pretty amazing thing and that it can be profitable is magic. Of course the environment and poorest pays some of the free lunch.

Many global indexes are also traded in USD.

Ironically last year has been good for those who held EUR based or CHF based indexes.