The thing with nuro is that he is at bottom - a failed normie. He wishes he had a wife, a job, a house etc. but he has failed to achieve any of these things and is all cut up about it. Some neets are, in material terms, not doing much better than him (eg. IGA) but are reasonably content to live the neetlyfe. Nuro despises it yet lives it due to his own fucked up nature.
He likes to use the board for escapist fantasy. He can pretend he is some successful normie with a job, a gf, lots of friends and money etc. I guess IGA acts as a mirror. He hates him because he sees himself in him, IGA reminds nuro of what he himself is. This is more or less what he admitted in the open love letter to IGA.