It's a fun theory that everyone likes to support but it falls apart when you read his Reddit account and realize he had insurance that paid for spinal fusion surgery and claimed to have no pain afterwards without the assistance of medication. That's probably also why he doesn't appear in any pain in his appearances since the incident, not because the NY DOC (infamous for their terrible healthcare) magically got him surgery instantly.

He became radicalized over time and even wrote that his pain was improved. Somewhere along the way he read something or got it into his head that he had to murder the United Healthcare CEO where he never was a customer. It was just one if not the largest healthcare insurance company.

I can’t speak to his thinking, but being caught with the gun used, and a confession letter…

Tells me he knew he was going to be caught and is angling for a hung jury.