Hotdrink's description of opportunity cost is spot on and a term used in Economics 101. Yes, staying home and/or homeschooling is a choice but with every choice there is a cost.
In my case, the opportunity cost is several times the cost Suri's school. Is it worth it? Right now, yes. Ask me again when the kids are having a meltdown over having to write a paragraph :001_unsure:
I will not begrudge another parent's choice.