To conclude, the story itself reveals things, that MC is hateful is to show the most realistic aspect of a human being, which is not pleasant at all, or may be for others. And that is taken care of in vol 3.
About the island, it is explained even in history, that there are undeveloped territories, so no one takes them as they seek to be habitable, the island was not habitable for humans, had no resources to explain, the water was polluted and poisoned sweet fruits, perhaps someone in the past discovered it and moved away leaving it in oblivion.
It is true that for an internal man of almost 40 years, MC behaves like a child, but that has its explanation, I am the author who always gives explanations and does not leave plot holes.
The narrative itself even explains many things, of which, are not even revealed to the characters, to maintain that "ignorance" of the world as we ourselves have.
Hi, I'm the author of the novel World Ixion/SAGA, I just wanted to tell you a few things that I couldn't say because the reviews don't allow it.
First, that you haven't read the story despite commenting on many things, what you say makes sense, but I recommend reading the whole novel or at least up to vol 3 so that you can see that MC is more human than "many are".