Lots of YT vids with that model. String together a bunch of related topics, copy/paste info from Wiki or some other source for narration, find a few related (or more likely random or straight up stolen) video elements to accompany the audio, post to YT. Some is okay but most is generic "meh" content. It's a view count generator, nothing more. TTS narration is easier, cheaper, and far less labor intensive than scripting, recording, and editing audio.
Creators can push out a couple a day, meaning cumulative view counts can be in the millions per month even if single videos generate only modest view numbers. That's decent money.
Brad