>> Something also tells me that if this guy wasn't absolutely stinking rich but was just a regular grumpy 70-something, there would be significantly fewer people fawning over his egotistical temperament.

You're forgetting the thing about him where he makes art that is unbelievably beautiful. He says himself he'd still do it even if his materials were worthless.

But who knows why people want to spend hundreds of thousands to own it.

"Let me tell you about the very rich. They are different from you and me. They possess and enjoy early, and it does something to them, makes them soft where we are hard, cynical where we are trustful, in a way that, unless you were born rich, it is very difficult to understand." - F. Scott Fitzgerald, "The Rich Boy"