I'm having a disagreement with my boss (a non-native speaker) who says that in this sentence the word "rigged" is a be-verb. I say it's the past participle acting as an adjective and I confirmed it with two other native speakers who have writing/editing experience (one even majored in linguistics and has two MAs in teaching to other languages). But my boss insists that it cannot be an adjective and can only be a verb and it shares the preposition "by" with "driven" but the agent is unknown.
I argue that if it were to share the preposition "by" then the agent is "greed" and yet "greed" can't "rig" something. However, I am struggling to find appropriate sources to prove either case. Here is the sentence in question:
"Cynics will tell you that everyone is selfish and weak, that the system is rigged and driven by greed, that you can never succeed, so it's pointless and contemptible to try, that all ideals are ridiculous, and the do-gooders are only out to show off their own supposed virtues."