You're moving the goalposts though, you realize that right?
Your initial position was that you have to have exploited people to be worth a billion dollars (with an implicit "directly exploited," since if you can't make any money without indirectly exploiting people, which would make your point even more pedantic than I'm being.)
Other people later exploiting others to profit off your product is irrelevant. Hell, it'd be irrelevant if you made your billion dollars and then started exploiting people yourself. You still would have, in fact, become a billionaire without exploiting people to do so.