Well the admin of a site could opt out of using cloudflare for the time being, a user could do literally nothing. Errors in Cloudflare can easily take down their servers and therefore the CDN and access to like 20% of websites. And Bugs in Cloudflare can even leak user data.

So cloudflare can grant DDOS Protection, CDNs and other exploiting protection, but can take down large parts of everything, temporarily or permanently.