rhiann, I think you've missed my point a bit.
I am questioning whether it's always healthy for a parent to invest their all in paying for their children's education.
If it means parents really struggling, moving home, moving jobs, working long hours, sacrificing a low paying but preferred career for a higher paying one, leaving friends and family, all in the name of school fees and a dream, then I think it can be quite dangerous.
Fine if you as a person are happy with your lifestyle. It's your life too. If however you as a person are not happy and resent the sacrifices, then it's a risky investment IMO. How will you feel if that investment doesn't pay off? How will you feel about your child?
Who knows what the future holds - a happy, bright and promising child can turn into a teenager at total odds with school. And what sort of burden does a teenager carry, knowing their parents have invested so much in their education? Aren't you raising the stakes, risking family harmony when parents put their dreams for their child's future in private education? Isn't it human nature to expect more of your children if you have sacrificed so much for them?
Now, as you say, exclusion can happen to any child at any school. No guarantee that in my husband's case, he would not have fallen foul of state schools too. But I wonder if his parents would have felt the quite same about his rebellion if they had not moved continents, left jobs, homes and friends for his education? I can't answer that of course.
I can make some guesses though. The effects of having a child excluded from a state school IMO is probably going to backfire on the averge parent a slightly different way. Most state school parents haven't made such huge lifestyle and financial sacrifices to give their child an education that is free.
Of couse any caring parent is going to feel upset about their child's problems at school. Of course lots of private school parents are not going to take it as a personal blow if their child fails at school. But I do think there must be an increased risk of fraught relationships between parent and privately educated child if that child refuses to toe the line. That's my own reason for not wanting to push private education on my children. We could only do it if we really struggled. Because of this, I do not want my children to carry the burdon of my dreams for them. But then, I have managed to find a good primary school for them, and ds1 is at a grammar school. Had they been at bad state schools, I might feel the sacrificace for private education was worth the risk to family harmony.
FWIW, my husdand was state educated in New Zealand for all his primary and some of his secondary years and got on fantastically - an eager, model student who dreamed of becoming a vet. The New Zealand state education system did him proud, but as many others have said, he was lucky.