At least in my experience, it's bars much more often than restaurants where the "Chad" douchebags turn up. Obviously the "instant asshole, just add alcohol" syndrome is at work there, and being in a bar band I've seen people at their very worst. Hecklers are one thing; I once made an unfortunate heckler literally cry after about two minutes of verbal abuse. But I've also had knives pulled on me (guy thought I was trying to pick up his girlfriend; it was actually the other way around), a full beer can thrown and narrowly missing my head. Rock and roll, as they say, is a contact sport.
Fortunately, those toads are the exceptions and not the rule. Being a freelance musician is a little different from being a server -- you won't be there after the weekend, so no one has a stake in helping you out, so you have to be able to talk yourself out of a jam, and willing to fight if talk doesn't work. But in a restaurant, this is where a good floor manager is invaluable, a manager willing to tell the Chads of the world to go fuck themselves, and if they want to play grab-ass and abuse the help, then maybe Applebee's or some such would be more to their liking.
Really, though, for me the question is much less political than anthropological -- who are the parents who raise these fucking assholes, and what emotional trauma did they inflict on them? Most likely, the Chads were spoiled and cosseted, never told "no", and so became used to getting their way. They sharpened their bullying skills in high school, on cheerleaders and/or nerds, and got out into the real world perceiving it to be, as Martin Mull once noted, just like high school, but with money.
So be nice to your server, tip them 20-25%, thank them for their work. And be warmed by the knowledge that, as cool as the Chads think they are, the fact is that none of their friends can stand them. And they know it.
And if, by some mishap, you happen to be in the same group with a Chad at a restaurant or bar, sit well away from them and do not get what they get, because I promise you, there will be mystery fluids in that fucker's food and drink.