Survivorship bias is kind of how capitalism works. The most unscrupulous ways are the easiest and fastest ways to gain money and money-adjacent things. Its not always good for long-term earning, but by that point the capitalists have moves on to something else leaving the workers to shoulder the loss. The less capable capitalists end up sharing that burden with the workers sometimes, meaning they end up not surviving to billionaire-hood.

Basically, to become a billionaire you have to survive all the other people trying to get there as well. Being more ruthless and more conniving, and more willing to throw others under the bus.

We can say there are exceptions, and Gabe and Valve certainly seem like ones... but as others have pointed out, they've resorted to less than savory methods on occasion to make sure they come out ahead. Its unlikely that its to an extreme reached by other industries (diamonds and chocolate come to mind first), but that doesn't mean they have no guilt to bear. Just more forgivable to most in light of alternatives.

I mean, math is the proof. Everyone who has become a billionaire utilized the labor of others to do so.