"Waste of money" is a loaded term, especially when considered in the context of necessities. If you reword it as "quality of investment" and "could your money have been put to better use spent on something else (or saved and not spent at all)", then it's a little easier to discuss and compare.

The assumption with buying vs renting is that your money isn't "working" for you when you rent. When you buy, your mortgage payments are going to build equity, and the logic used is that it is a "forced savings plan" compared to renting, where once you pay your rent, you'll never see that money again. The inverse, which is implied, is that you will actually see the money you pay for the mortgage at some time in the future. As everyone found out, that's not necessarily the case.

In my case, I lost money on the sale of my house, for various reasons (economy, improvements, agent fees, taxes, buying to live in it vs buying it as an investment, some of which were under my control, some of which were not), such that I would have been better off renting the whole time. I, personally, lost about $10k. Had I rented in the neighborhood instead, the savings would have been even more drastic because I wouldn't have needed to spend so much, per month, on housing, despite being able to live in the same area and have the same amenities.

The real value in buying a house though was that I learned exactly what it means to own a house and exactly what is important to you (in my case, location is much more important than size), which I don't think you can learn any other way. There really needs to be a perfect storm of positive variables, in the last few years especially, to make money on owning a house. My home buying years have not, and will not, be marked by such an increase in demand and rise in prices that the sale price offsets all the other, financial and emotional, costs.

I joke about setting a personal requirement of 80% down on the next home I purchase, if I ever purchase another.

Owning a home long-term after the adjustment will be a great investment in the US, I imagine. The US is a debtor nation. The debt can be paid off by printing currency (perhaps gradually). This will cause inflation as more dollars chase the same amount of goods and services. Your mortgage debt dollar amount remains the same, but gets paid off with new, cheaper bills.

It's a waste of money in the same way that the interest portion of a loan payment is wasted. When home prices are not rising astronomically, that "wasted" interest will be a larger drag on the overall investment.