Well, it's throwing away money compared to home ownership, which also gives you a place to live. I don't know about hypothetical ultra-liquid markets, but in practise rent is usually higher than interest+maintenance fees over a longer period of time. Real estate investors need to make a profit, and so do banks, but the banks tend to have slimmer margins.
Also, banks are often still making a profit with rental properties.
Which isn't to say you should buy a home blindly - you shouldn't do anything so major blindly. It seems to me the appropriate way to view it is: if your cost of owning a home sans payment of principle is less than renting, then you are "throwing away" money but the alternative is investing that piece you're throwing away plus quite probably more in the real estate market, with the corresponding potential upside and risk. In the extreme case where costs including principle are less than rent, then you should probably purchase. An additional thing to watch, though, is that people often under-estimate things like repairs.
All of which is to say, there is no obviously right answer.
> Well, it's throwing away money compared to home ownership
It's still not "throwing away money", there are just different things that people value. I value being able to move whenever I want, wherever I want. To me that is worth potentially paying more. The same way some people value being dropped at their exact location with a taxi vs a close location with a bus: just because the bus costs less does not mean you are throwing money away with a taxi.
