[CrazyStat]

I know a billionaire who basically was in the right place at the right time during the biotech boom. He started a company as a side project (he was a professor), got a deal to supply a major pharmaceutical company, and expanded from there. I don't know every decision he ever made but I'm not aware of any unethical behavior. He lives fairly frugally and has made a point of staying under the radar (he's successfully avoided being put on Forbes's list of billionaires, for example).

I'm willing to argue that it is in fact possible to become a billionaire though honest earnings.

[Miraste]

I probably shouldn't make such absolute statements, they do beg for counterexamples. I'd be surprised if your friend didn't engage in some anti-competitive or employee-exploiting practices, but of course I have no idea.