The level of detail is very nice, I wish more tools exposed this as easily. That said, please remember this is a test of you through your ISP to a (hopefully) nearby Cloudflare node. It isn't necessarily testing 'the Internet', since Cloudflare sometimes has creative peering relationships to origins that are not being measured here. Also, for the people complaining they only have 300 Mb/s -- unless you are streaming…
Well, having a good network card and frequently downloading large files (which I'm guessing lots of people do here, especially those in ML/AI and related fields), I'm not sure why the downloads wouldn't go faster if you didn't have more bandwidth... People use the internet for more than just watching movies you know.