Oh…I forgot this part of my answer.
My kids went to public school through 12th grade…and both went to private colleges.
@oldfort makes a good point about what is the case in certain areas. Here…in my area of CT, there are a lot of options for private prep high schools…but not very many options for prek- grade 8.
We live within easy commuting distance of Loomis, Hotchkiss, Taft, Westminster. All HS programs. The only private day school within a reasonable commute is Renbrook in West Hartford.