It just depends on the difference between what you can get today, and what you expect to get in the future and when.
If you discount it to 80% today and then rent it at that rate for 10 years, you'll lose 10% compared to if you leave it empty for a year and rent it for 9 years at 100% of asking price. Obviously financial calculations have a lot more complexity than that, but it illustrates why someone would prefer a vacant property. It's based on expectations of future income.
And that doesn't even factor in what also happens a lot in NYC, owners wanting to redevelop. Your building sits empty for a while, as horrible as it sounds, it can speed approvals that you might not get if they were full. Never miss an opportunity to take advantage of a crisis, and a crisis like the pandemic doesn't come along very often.
The fundamental problem is everyone wants in on the big money. No one really wants to serve the lower end. And the lower end would be upper middle class in some cases in a lot of other cities. Definitely all of it will concert to make parts of NYC the exclusive domain of the wealthy soon. (Actually, parts already are, I guess I mean more parts.)
Not filling at all should too though.