cybernetics makes you evil. No, fuck you Pondsmith, there is no way to make cybernetics mechanically reduce your humanity that is not inexcusable ableist bs. Let it die.
now my guy is a flaming
but he does seem to give that choice to the dm. Within universe there's at least three explanations for cyberpsychosis;
AI takeover (there's also the idea that the AIs beyond the Blackwall are actually demons and that a secret cabal has been upholding the wall since Babylonian times), planned obsolescence by the companies(checks out tbh), and then the one that you referenced, which is loss of humanity and not seeing other people as humans anymore.
overall it's just a balancing mechanic, Shadowrun does it better though 