Some communities highly dissatisfied with their police attempted to defund and/or defunded their department. That's not a great example because self-service policing doesn't work very well, but it's kinda close.
Ultimately, if you want the voters' money, you need to convince them that you at least won't use it against them. And it's really easy for people to start thinking that it's being used against them when engaging in culture war or political issues.
This is a great example for what should happen - demands for systemic reform, not taking what you think is "your" money and going home.
It's one thing to opt out of a system, it's another to think you're justified to get money back for it. As someone without any children am I justified in getting 24k/year back because I'm not using the school system for my (average) 2 non-kids? Of course not, but I do pay taxes for that service.
Ideally, it would be a back-to-basics reform that would be more neutral. But probably what would happen is a slow draining of the best students along with money until it spirals.
You can say that shouldn't happen, or be mad at the people who opt out, or be mad at the people who underfund it. But it would be better to save it by at least making an effort to be neutral before it gets to that point. Too many teachers look at students as their children to mold according to their personal or party values rather than educating them according to collective or neutral values.