I don’t know. Certainly, at a certain income level, private school is a non-starter without financial aid. It just isn’t doable. However, I think some of it depends on how highly you value a boarding school education and also whether or not your alternatives (at a local public or independent school) will be good enough experiences for your child.
We are not even close to a full pay family at my kids’ schools, but I actually think the calculus is the same (and highly personal) whether you are full pay or your kids receive FA. I don’t think there is anything wrong with changing your lifestyle in order to pay for K-12 or college tuition.
My rule of thumb is that I was unwilling to penalize my younger children (much) to send an older child to boarding school or college for that matter. That means that I wanted to still be able to pay for some of the younger siblings’ discretionary expenses like soccer/dance/music lessons etc. On the other hand, I was absolutely willing to give up family treats like travel and eating out. I was also willing to live in smaller apartments, make my kids wear hand-me-downs, curtail some summer/camp choices for my younger kids, and insist that my teenagers get jobs to help cover their personal expenses. I would argue that some of the choices that I’ve made qualify as our lifestyle being materially affected by tuition payments. Were those painful sacrifices to make? Yes, absolutely in some cases. Were they impossible sacrifices to make? Nope, I think my kids’ K-12 education has been worth it.
Finally, one thing that I noticed after the eldest headed for boarding school is that certain household expenses went down with her gone. And I was no longer paying for some out of school activities because she was doing those activities at school as part of the all inclusive tuition.