I'm not a huge fan of Zuckerberg in real life - I admire what he's done, but not his personality. But in the movie, he's written to be the hero, a hero with flaws certainly but hero none-the-less. So yes that's certainly part of it, but just as he was written to be the hero, so too were the twins written to be the bad guys, even if they weren't as bad as we might expect hollywood villains to be.

I don't think egos is weird to parse, they didn't just come from money (incidentally I come from money, to a lesser extent, so that doesn't set me automatically against people), they were the type of people that think their coming from money makes them superior in more ways that just their bank account balance.

As to money-grabbing, it's my opinion both from the actual story and also the movie, that they frankly didn't deserve the money they got from Facebook, so yeah they were money-grabbing in their legal pursuits.