For content delivery you can simulate the load one PoP would get. You don't need to be at Cloudflare scale to build a testbench with 800G+ of traffic at different pps.
If it's so easy, why hasn't the next Cloudflare-destroyer shown up yet? Anyone?
There's more to building a successful CDN business than running workloads in a testing environment.
It's a capital heavy investment in an already crowded marketplace (there are many CDN companies well predating Cloudflare) with little guarantee of return on investment. Who are you expecting to show up? If you want alternatives, there are plenty, for specific products/features.