I'd say because they ultimately never generate enough revenue to pay rent? Failure is the final destination of pretty much everything that is ever built - it's

I'd say because they ultimately never generate enough revenue to pay rent? Failure is the final destination of pretty much everything that is ever built - it's a good thing some at least have the luck to be "acqui-hired" in the end... (the fact that many start projects with that objective in mind doesn't help to improve these numbers either)