I agree that AI psychosis is a real risk in vulnerable populations (GPT-4o in particular seemed borderline predatory towards those types of people, with its extreme sycophancy), and you should remain clear-eyed while using models. That said, I think exhibiting basic courtesy is still well within the safe-zone. I guess we'll see - I'll be sure to let you know if I end up going psychotic.
Personally, I think having to constantly mode-switch between "courtesy / collegial" and "terse / cold" is a bit exhausting and a little risky. What if I get tired and accidentally treat a human co-worker like a computer? Risk with no upside. Might as well just stay in "courtesy / collegial" mode for all of my conversations, regardless of whether I'm talking to a robot or human.