Someone who does this has a strong need for attention and belonging to a particular in‑group that they ignore most societal norms.

They have a very low concern for how distressing or hostile this looks to others, which can overlap with traits like antagonism or narcissism.

What you can reasonably infer from a car like this is: strong identification with polarizing politics, comfort with provoking or upsetting others in public, and a high need to broadcast grievance or hostility; those are compatible with higher dark‑trait scores.

While not specifically “mentally ill”, they exhibit traits that are socially unacceptable and very likely to be irrational, hostile, and generally unstable. But at least they label themselves as someone to avoid at all costs.