> And here I was going to suggest that billionaires, unbridled mega-corporations were the fundamental risk to the existence of human civilization.

Depending on the measure [0], it's possible that the richest billionaires and least-bridled corporations are both well in the past. Human civilization survived, and will continue to survive.

[0] https://en.wikipedia.org/wiki/List_of_richest_Americans_in_h...