Could be a money maker for the right investor. You turn the actual silo into doomsday apartments and charge a minimal monthly fee (since they aren't actually living there), but set terms on what defines an emergency, etc. and you could really bank. Of course, the startup cost to transform it would be enormous, but I bet you'd make it back within 5 years if you marketed it right. (the money to convert into apartments, not the initial house buy).
Downside is, all these folks that would then be your responsibility come SHTF. Get a small security force that get free apartments, so if the SHTF, they will be your enforcers. Would have to have a way to provide food and water for all, as well as electricity, etc.