Unless you're serving something, you should probably drop all incoming requests. If you are serving something, the US is a pretty big market to lock yourself out of.

FWIW, I blocked the US for a while.

Eventually, my lets encrypt cert expired and it turns out certbot is run from USA, so the auto renewal failed me.

Almost all spam traffic comes from the US, it's not even close. But for many people so does much of their human traffic.