I can't speak to everyone's motivation, but for me YouTube, and only YouTube has the kind of fascinating niche content that I want to watch. Often that content is created by random people who have a passion and zero profit motive, which makes it more authentic and charming. Sometimes it's an elderly Mexican grandmother explaining how she makes Chilaquiles[0], or maybe it's someone explaining why the Great Reform Act of 1832 was necessary[1], or perhaps it's a professor doing a deep-dive the history of the Vulgate and the life of Jerome[2], or maybe it's a YouTube series[3] that dives into a huge rabbit-hole (pun intended) on restoring a weird 1980s minicomputer -- whatever interests you that moment, someone is likely passionate and knowledgeable about it, and has made a video on it.
[0]: https://www.youtube.com/watch?v=4mQx1zzBpuU
[1]: https://www.youtube.com/watch?v=U_9PGNHd5Zs
[2]: https://www.youtube.com/watch?v=EF98_HnYHjQ
[3]: https://www.youtube.com/watch?v=DJ1HwuYBuss&list=PLnw98JPyOb...