Indeed, there are disadvantages to being the world's reserve currency. This is known as the Tiffin Dilemma and was articulated in 60's:

https://en.m.wikipedia.org/wiki/Triffin_dilemma

Basically this is why times have been great for industries like finance and tech in the US, but sucked for manufacturing. In turn leading to wealth inequality and, dare we say the class struggle that seem to have reached a boiling point.