That's not exactly what is meant by luxury beliefs. Luxury beliefs aren't simply beliefs that rich people hold. It more refers to social opinions which would (allegedly) impose high costs on the poor, but from which the wealthy would be insulated from the consequences. Something like "defund the police" is usually pointed to as an example of a luxury belief. The poor, who live in high crime areas, would see crime go up and bear the brunt of the consequences. Whereas the rich, who live in pricey, low crime neighborhoods, wouldn't see much of a change and would be able to afford private security anyhow if they did.