I feel like this sentence gives us a lot of insight what the old man is like. He is a a very philosophical man and it feels like he's been through a fairly severe existential crisis which could've ended bad. It is clear that he's contemplated a lot on whether God is actually real and if there's a possibility that he is a god. I suppose he's concluded that a person isn't capable of fully understanding the question and has decided not to worry about it.

As we all know, it's pretty hard to hear someone talk to you on a plane, even if they're sitting right next to you. I assume that's why the man felt like he needed to repeat himself to get his point across.

I suppose if someone's already hardboiled an egg, there's no world to destroy anymore. I suppose that's why the man didn't further ponder over whether he should eat the egg or not.

If we measure one's value as how much impact they've had on humanity's quest to find the absolute truth, then I definitely agree with the man. Imagine you come up with a groundbreaking theory about the perception of the universe and it gets absolutely ignored because you have a successful music career. Of course, being a music artist has it's own perks, but it would really suck to see people's ignorance towards your intellectual ideas.

I highly disagree with this. I am probably missing something essential here that would explain this claim, but the entire reason why Hesse wrote this was so Sinclair (the protagonist of the book Demian where the quote is from) would realise that he has to step out of his comfort zone to become a new person and "destroy" his former self. Maybe the reason the narrator hates Hesse so much is because he's had enough of his metaphors.