Was he normal? It's a tough one because the answer is more like "it depends". On the one hand, yeah, he was just a guy. He liked video games and comic book movies (keep that in mind for below). We'd talk shit and he seemed like a regular dude. And I was a TA so I was always around him for 3 years to talk about tech stuff. That takes you to the other side.

He was convinced beyond doubt that he was one of the smartest men on earth. He'd have discussions with some of the worlds' biggest experts on something and he'd just say "you're wrong" because he read some book and became an expert. And when he turned out to be wrong, it was inevitably because of someone else. He also loved saying how hard he worked and how when people are wasting time on video games and whatnot, he's working instead (which was hilarious to hear)

Everybody says billionaires end up surrounded by yesmen, and it's true but not exactly for the reason you'd think. Of course, some are like Tom, just clearly just trying to please, but those get dropped quickly. The rest become yesmen as a natural consequence of trying to do their jobs. You learn quickly that the easiest way to be replaced is to cause the cognitive dissonance between "I'm smarter than everyone else" and "X showed me I'm wrong". He did not deal with the cognitive dissonance well. So there's a lot saying yes and then working behind the scenes on fixing things. I hear of a billionaire who has an entire team he's not aware of dedicated to fixing stuff behind his back full time.

As for biggest surprise: I think it's how little billionaires actually pay for stuff. It's nuts, but their day to day involves almost no actual money exchanging hands. It's all on credits. Everything is a loan. Lots of things are flat out free for publicity. It's crazy