When you're hellbent on becoming the #1 OS in the world, making the #1 MP3 player, or the fact that your company's market value went down a billion dollars in the past 24 hours
I think that in the case of Gates and Jobs, they're not personally hell bent on those particular things. They're both very driven people, but you can be pretty sure Jobs isn't aiming to make OS the biggest in the world, or even have iPod be #1. Sure he'd like that, but it's not what he aims for - he aims for making a better experience, a better OS, a better MP3 player. If it turns out that those things become #1 in sales, then great, but that's not his end goal. Likewise, in hearing Gates talk, aside from his philanthropy, he seems to want to find the next big thing, create the sci-fi future where we have ubiquitous computing, etc. He's not out trying to crush Apple or anyone else.