My perspective has been sobered quite a bit over the years - these things are rarely as simple as we might imagine they could be - but it remains heady stuff. I can see how it might give the right kind of person delusions of grandeur.
The egoism on display here is pretty offputting, but I feel kinship with the "dreamer" mentality underneath. This guy had a vision, and he was uncompromising in his pursuit of it, and even if the end result wasn't worth much to anyone else, some part of me has to respect that.
I'm reminded of The Room (movie)'s Tommy Wiseau. Another creative who thought he was a genius and poured his blood, sweat, and tears into his life's passion project, and it turned out to be pretty objectively bad. But it was meaningful to him, and there's something to that. There were no ulterior motives; he wanted to put this piece of himself out into the world. There's a purity of spirit. I think what's missing for these individuals is the self-awareness to know that this thing is mostly just for them, and to be okay with that idea and embrace it. That way lies happiness, I think.