The sheer magnitude of video data they have to deal with is enormous. They, along with netflix, comprise the majority of all internet usage. Yes, the videos you see on your front page with 10s of millions of views are raking in the cash and have negligible hosting cost. Those videos are subsidizing the 10s of millions of videos that get 4-5 views apiece.

I've heard the line they're right on the edge of profitability but I've never gotten any real confirmation. I was younger when I heard that and I always though youtube was just a cash cow. But think of how much servers (huge streaming metrics for each person watch + encoding servers), bandwidth and CDN must cost them. Ever with their own cloud, that has got to be huge. I worked at Amazon Instant Video and our CDN bills made my eyeballs pop out like I was a loony toon character. Traditionally they've only made money video advertising but I'm just not sure thats a great business model for video anymore. And, also throw in live streaming that people have been using, especially during covid, which is also free, and you have even more load they pay for free.

An idea I always had was embedding a big zip or something into the mp4 format and uploading it for storage. Would they save the original files for download or would they be encoded to a lower bit rate and make them unusual. Maybe data encoded in an audio track would be better? Sounds like more than a weekend of experimenting but would be a cool little project.

Server and storage costs must be astronomical - last time I checked something in the order of 48-hours worth of content is uploaded every minute. Coupled with the fact that they've had a couple of issues with advertisers leaving or withholding spending, I doubt what they pull in is enough to cover expenses.

Like others have said, their storage needs are staggering. I would not be surprised to find that YT's storage is bigger than the entirety of Google's web archive, which is mostly text. Possibly much bigger.

If YT were not part of Google, they would still need Google-scale infra in order to handle the insane number of pixels they're streaming every second of every day.

Well just think about how much it would cost you to host, encode in many many formats, billions of hours of video, consuming exabytes of storage, providing a fully reliable service for 15 years.

Might also be worth considering why there are effectively zero competitors.

Their transcode, storage, and compute costs are what lead me to also believe YouTube is not profitable, or just barely profitable.