I am CFO of a management company who own and manage only storage facilities.
A very lucrative business if run correctly, but like any business, there is more to it than you think. The building of a facility will take a while and will be expensive, and then must be leased up, which, if you don't know what you are doing, could take some time.
Purchasing an existing facility is another idea, but most on the market are very overpriced.
Hurricane insurance is not as expensive as you would think, but it depends what your buildings are made out of. Most here in Florida are concrete due to code, and some of our facilities could probably be used as shelters. Theft is not so much an issue either, at least for us. Security cameras are definitely a must for your facility, as customers must feel like their stuff will be safe. I have heard of a few incidences of theft, but the cylinder locks are very hard to drill through, and people don't generally carry around lock cutters with them. Access to the facility is limited to those who are renting there as well, so it isn't like there are a bunch of people inside the facility at 2 AM. Our facilities do not allow 24 hour access. Again, it could happen, but it is also the tenant's responsibility to carry insurance on their belongings, as well as lock their unit, and they sign a lease stating that they understand that their goods can be stolen, and that the facility is not responsible. Have never been sued, and have never heard it happen. Have never seen a fire at any facility, either.
If you are looking to build a cheap facility with no security cameras, piss poor gates, and non-theft proof units, then yes, theft is a problem, but this business, like most others, is a take money to make money proposition. If you do it right, then money can be made, but not all areas of the country are "right" for storage. South Florida is, because of no basements and lots of people who can't part with their belongings.
HW