>>113368506Yes, extended stays would make someone lose their sanity, sense of self, and apparently even their humanity, there doesn't seem to be evidence of the island and/or realm receiving nourishment or energy from them. I believe it's simply their bodies responding to the dimension, and being unable to keep up. If you recall Captain Elmer, he was suffering physical degeneration, his body was literally falling apart. Could also explain that one researcher lady that exploded. Perhaps given enough time, someone will eventually die inside there. I don't think Endless is truly hostile, merely too alien. It's some kind of place where normal laws of reality doesn't or perhaps can't even be applied. The toll of the human body and mind in response to that must be immense, especially towards adolescents.
Beings like the Butt Witch and the islanders can't be affected by its usual effects because they're not human or at least organic in the typical sense. I think the resentment worms arisen simply because the dimesion was responding to the trio's feelings, and late into the series, those negative emotions were at a threshold. If the Island was trying to consume Butt Witch, then I believe it would have released the worms much sooner.