I think your parent comment is neither here nor there on actually leaving, but rather just using hyperbole to demonstrate that this isn't a problem easily fixed with laws.
A food establishment forced to serve you might serve you food that's gone bad, a mechanic might not fully tighten the nuts on your brake pads, or any other variety of horrible things that people could do to harm you while leaving room for plausible deniability.
At least if they can legally deny service to you, you know that the ones serving you aren't a risk to your wellbeing. And to that end, I think it's a bit unfair to suggest that less money means there would be no businesses to serve that group of people. If every restaurant is discriminating, the singular restuarant that serves the less wealthy group would have plenty of business, simply due to the lack of competition.
The "pro-regulation" argument is valid with regard to a less commoditized market though, which is interesting. For example, I wouldn't want the only company that makes a life-saving drug to be able to legally discrimate who they sell it to.
It's a challenging problem and I certainly see both sides. My gut goes to regulations affecting large businesses but not smaller ones. It feels like there are probably some difficult edge-cases within there though.