I wasn't able to find an official source for what YouTube's total data storage is, but this estimate puts it at 10 EB or 10,000,000,000 GB of video.
On Amazon AWS that would cost $3 Billion per month to store. The actual cost to Google is probably much lower because of economy of scale and because it is run by and optimized for them, but it is still a colossal figure. They offset the cost with ads, data collection, and premium subscription, but I would imagine running YouTube is still a net loss for Google.
Not that it makes much of a difference, but storing 10 EB on AWS S3 is more like 300 million USD a month. With some tiering options you can reduce that a bit further, but still it's a huge number. Following your link you seem to have used FSx Lustre for calculation, not S3.
That calculation may also take into account upload and download bandwidth. And I know there are like 100 different cloud products in the AWS console. I don’t know much about high scale performance tuning but I bet dozens of those AWS services would be involved in something like youtube.
Just to put the storage issues in perspective, a minute of HD video is about 120mb. Moby Dick is 1.2 mb in plain text. So for every one minute of video, you could store all of Moby Dick 100 times.
It's not peer to peer though. It's similar to Lemmy and Mastodon where someone hosts an instance and serves video from that. Except with video it gets very expensive, so I don't think server admins want to see a migration happen.
A peer to peer solution would actually be cheaper for everyone involved.
YouTube basically killed all of the original video sharing sites because it was so convenient. The cost of setting up and running such a site is astronomical.
Videos take up a lot of storage space and require some serious hardware specs to properly serve to users, no matter how much computer science wizardry you use to compress them and reduce their load.
It also becomes far more difficult to moderate and monetize such content. I bring up monetization because it is a damn necessity to keep a platform like this running. No amount of donations, voluntary moderator hours, FOSS packages or copyleft pipe dreams are going to pay for the financial and personnel costs of a large video site.
Many competitors to YouTube have popped up and failed like VidMe, Dailymotion, Break, Blip, Vimeo, Bitchute, Storyfire and oh so many others. The only one that has even managed to compete with YouTube came from a massive Chinese state sponsored tech firm (TikTok.)
And before you mention Rumble, they're pandering to a very specific niche of controversial right-wingers who have been largely deplatformed from mainstream social media. If it weren't for Donald Trump and Andrew Tate, they would've shut down years ago. Kick meanwhile is basically being bankrolled by a crypto slot machine website and is only attracting streamers because of how badly Twitch have enshittified their platform.