An original piece doesn’t necessarily have to be in a public location to be viewable by the public. Copies are very common, and legitimate. Wanting to have an original piece of art in your home makes perfect sense. Its like collecting antique cars, or anything else. Its a way of feeling connected.
To own something beautiful isn’t a gesture of luxury, usually, but a gesture of admiration.
Also, if you didn’t have private patrons, we wouldn’t have any high art at all.