And in the meantime, they choose not to rent it why? The intuitive answer is: they're hard to rent, because there's way more luxury condos available to be rent

And in the meantime, they choose not to rent it why? The intuitive answer is: they're hard to rent, because there's way more luxury condos available to be rented than people who want to rent them, and it was a bad investment that the rich person will probably lose money on (if not in absolute dollars, then in comparison to some other property that is desirable to rent). But a lot of people in this thread seem to think it's intentional and rich people have some devious way of making more from a vacant condo than a rented one.