The US Dollar Index (DXY) measures the value of the US dollar relative to a basket of foreign currencies. It goes up when the dollar gains value relative to said currencies and vis-versa.
The price of DXY is inversely correlated to BTC and other crypto assets. This makes it very useful to add to a crypto portfolio, as an asset to rebalance to during drawdowns.
I support adding, but currently there are much bigger problems with mirror, than lack of mAssets