I've always been a firm believer in the saying;
Education is not the filling of a bucket, but the lighting of a fire!
So, is it a waste? Actually, for some it is.
Notice that I didn't isolate that to stay at home moms, this applies to everyone who pursues education. The onus is on the individual to determine how fruitful or pointless their education will be.
When I was in college I saw the whole spectrum as I'm sure others have as well.
There were kids right out of high school who were taking classes simply so they could continue to live at home for free- because mom and dad had told them that if they didn't go to post secondary they would have to get a job and pay their own way. For many of these kids, it was a complete waste because they didn't understand what they were doing and didn't really learn anything from the experience and most importantly they didn't care. They were just happy that they were avoiding the move to adulthood. Yes, they went to class, at least most of the time and usually passed their courses but it was of absolutely zero benefit to them. Some of them, however, woke up part way through and discovered higher learning and hard work and all that feel-good motivational poster stuff, and for them it definitely was not a waste.
There were single moms working two part time jobs, looking after their kids and losing sleep to study in the quiet hours of the night so they could make the grade. They definitely understood why and what they were there for, but the circumstances of their life really made it difficult to succeed and you couldn't help but feel for them.
There were also dads doing the same thing, but I noticed most of the dads were in a relationship whereas a LOT more of the moms were single. Not being biased, just an observation. This changed the dynamic a lot- whereas the single moms had the weight of the world on their shoulders and had to do EVERYTHING, the dads tended to have more pressure/troubles keeping their relationships going and communication problems with their spouses.
Anywho, for both the moms and dads, single or otherwise, it definitely wasn't a waste!
Then there was the "entitled" crowd, as I believe Tova has documented quite well in her postings about her current experience. These are the kids who are generally pretty smart and get good grades without even trying, but are incredibly stuck up and believe that the instructor and classes have been tailored entirely for them. It's quite interesting to see what happens when one of these folks gets a C or D on an exam and the hissyfit they throw, sometimes even dragging their parents into the fray. For some of these wizz-kids, yes, it too is a waste because according to them they already know it all anyway. This is sometimes legitimate but mostly not!