the world's reserve currency can have huge falls, it went from an exchange rate of $0.9 to 1 euro in 2001 all the way down to $1.47 to 1 euro in 2008 thats a huge fall for international investors. Remember 2001 was also the height of the first US tech bubble which resulted in huge falls for both US stock markets and dollar, very painful for international investors. I was an investor in US stocks back in 2011, and it was great buying them when priced in cheap dollars back then.I have generally considered this a positive and not a negative. World's strongest market and world's reserve currency.
Of course the Trump tariff thing is having a short term positive for US dollar but that is actually going to make the US even more expensive and uncompetitive, its very early days in the Trump thing. Every dog has its day