Well, i checked. From the top 1000 websites in the world, cloudflare is fronting 55% of them.

Same with top 10000 websites, 55%.

Top 100000 websites, 52%.

All measured websites, 29%.

I think this is telling a different story than small sites using free cloudflare services. The 20% that cloudflare says is most similar to "all measured websites" where tons of small ones are included.

Something like 40% of the top 100k sites use Cloudflare. Builtwith says 44%: https://trends.builtwith.com/websitelist/Cloudflare/High-Traffic-Volume

The pricing on their paid plans is very competitive. For small to medium sites, it's orders of magnitude cheaper than Akamai. The WAF and DDoS protection is pretty good too.

The largest sites like Google, Facebook, Netflix, etc have their own CDNs, including servers they provide to large ISPs for free since it significantly reduces upstream bandwidth usage (Netflix call this Open Connect; Meta's is Facebook/Meta Network Appliance). Outside of the largest sites, you'd be surprised how many companies rely on Cloudflare. It's kinda scary.

I suspect most of the paid Cloudflare customers are also AWS or Azure customers. Cloudflare isn't used to host big websites, but it's certainly used to defend them from DDoS attacks, which is the main feature Cloudflare offers and what is usually in use when you see the Cloudflare error page.

Cloudflare for hosting small static websites is a niche usage of it.