I don’t know dick about the internet but what exactly does cloudflare do for a customer like KF? And what are the barriers to entry to start doing it yourself?
Say you run a website, which is just a set of files on a computer.
And say you piss off a trans paedophile/child groomer. That trans paedo might contact some of their dark net file trading partners, and find one who has control of a large number of computers that have been hacked and taken over. These computers are referred to as "bots", and a collection of them is called a "bot net". Often the owners of these computers don't know they've been taken over, as smart people who run botnets try and stay under the radar, lest Great Aunt Bertha starts wondering why her computer is running slow.
This trans paedo could pay the owner of the bot net to tell the bots to all access your website at once. This will rapidly overwhelm you lowly computer, as well as cost you huge bandwidth costs. This is called a "Distributed Denial of Service" attack, or DDOS.
Cloudflare have a shit ton of computers all over the world, that stand in place of various websites. When you go to (say) Kiwifarms, you actually go to a Cloudflare server near you, that has as much of Kiwifarms stored locally as it can. The header image, people's avatars, whatever. That means when you go to Kiwifarms, the Kiwifarms server has to do less work to provide the page, as much of it is cached. Because Cloudflare has billions of dollars in infrastructure, if the trans paedo wants to overwhelm your site they have to rent zillions of bots to overwhelm them; and if they don't rent enough nothing happens.
The other thing Cloudflare do is have full-time staff and AI studying botnets and designing mitigations against them; meaning the trans paedo has to spend even more to make a dent on the site.
If I'm right, then some trans paedo is about to launch a sustained DDOS attack against Kiwifarms now that Cloudflare aren't protecting them, and try and put them out of business.
As for setting up your own, feel free to do so; but it's expensive and you need lawyers to explain why you're hosting content that fat bastards in Milwaukee find both accurate and offensive.