Forget all the stuff out there that says the GDPR protects EU citizens. This is a question of jurisdiction and enforcement. Say I run a blog under a business registered in the US funded by advertisers in the US. A EU citizen that comments on posts issues a GDPR request that I ignore. Their government fines me. I tell them to get bent, I am out of their jurisdiction. What can they do at that point?
Then they block your site and prevent you ever doing business in one of the world’s largest markets. I’m not sure how liability works but the CEO may also be unable to travel to the EU also