Certainly everyone else at his high school could have been doing what he was doing. I'm sure this wasn't the only high school like this, though the number may have been small.
I don't think people are arguing Gates didn't do anything to warrant his success, but they are saying that if he hadn't been afforded early opportunities significantly more advanced than perhaps 99% of other high schoolers in the US, or 99.999% of other high schoolers in the world (and I don't think that's an exaggeration - seriously, search for articles about how his HS computer system was networked in with U of Washington ... in the early 70s), that he wouldn't have been nearly as successful.
