How do ppl get away with posting self made audiobooks to youtube?

There are a few unofficial audiobooks I've had the pleasure of listening to on youtube. One of the narrators has mentioned how they've had to move some of their readings to patreon bc their vids were getting taken down from YT. On the other hand, some of the unofficial readings, which are not of public domain books, have stayed up for quite sometime.

Im really curious how this works out legally. Does YouTube just remove it as copy right, and that's that? Or is there a strong possibility of the unofficial narrators facing legal consequences, like being sued? And just how closely are they riding that line by encouraging for readers to go pay for their patreon to hear the readings? Hell, how closely are they riding that line just for having it up for free on youtube?