You're also missing the point that people are criticizing a systemic issue. It doesn't matter if there's a single billionaire who didn't exploit others, it's the overall system that keeps on promoting it that's the core of that particular issue.
But also on that note, there isn't a single billionaire who didn't gain the vast majority of their wealth directly through exploitation. That's pretty much just a basic economic fact. There's just no other way to amass that much wealth.