1 billion people would certainly disagree.

I think what he's saying is that all seven billion of us benefited from the PC revolution, where the bottom one billion may benefit (or may not) from Gates' efforts.

It's an interesting ethical question. As with most questions, I don't know the answer to it.

Exactly. Also indirect effects, like how much more productive are cancer researchers thanks to computers. Very hard to underestimate the importance of computers.