That's interesting.

Cloudflare says on their homepage "Everything we learned from powering 20% of the Internet". But I wonder what they mean by 20% of the Internet, is it about sites or traffic?

They also say "Cloudflare powers 45% of the Fortune 500" which correlates with your numbers.

So 29% websites, 20% traffic and 45% of F500 seems reasonable, where other 71% is shared between AWS, Azure, smaller CDNs and those brave people not using CDNs at all.

The other poster also shared a link where stats seems similar for CF(~1/3) https://trends.builtwith.com/cdn

Still very far from "the entire world" claim in OP.