Not a lot of Biblical citations (I think I counted a total of three) for a supposed Biblical treatise on "Doomsday Preppers."
With that said, I agree that ANY obsession that detracts from one's relationship with Christ or heavenly purpose here on earth is a sinful obsession ... an idol. The premise that those who prepare for difficult times are obsessed is, however, flawed. Flawed premises are fairly common when you lump people into groups and make assumptions about them.
At an individual level, obsessing about doomsday preparations is no different than obsessing about food or video games or guns or ... anything else that gets between you and God.