Exchange rate risk can be hedged. In simple terms, the hedging cost is the interest rate differential between the two currencies plus a small risk premium.
I haven't done any currency hedging for quite a few years so I'm a bit out of touch. But I'd be surprised if an AUD/USD hedge currently costs more than 1% p.a. That's nothing compared to the 66.8% p.a. profit scenario I posted about.
