It's also one of those things that's easy to talk about when you've never "been there". It's easy to say "what's the difference between 30m and 20m a year? Both is paying me more than I could ever need. I'd happily take 10m less to help my team win". But I'm willing to bet that quite a few of those guys who are making 10, 20, 30m are also guys who have previously said "it's not about the money" or "I'd take less, I don't need that much" or whatever.
Talking about it in theory, purely as a hypothetical is awfully easy. But I think most of us would probably have to admit that if push came to shove and our boss came to us and said "Would you like your salary to be 30m or 20m this year?" that just about everyone would say 30m without thinking twice.