I block Russia, China, and Iran from my sites. They represent 0% of the revenue, and 99% of the login attempts.

Yeah. In the same vein I also don't distribute my app in the Play Store in certain countries. I realize it completely sucks for them, but it's purely a business decision. Certain countries are just very vocal in terms of negative reviews, simply swap 5 star and 1 stars due to cultural differences, and also bring in almost zero revenue. The net result of distributing in these countries is literally negative: they hurt my ratings and reviews and don't make up for that in terms of money.