At least in Ohio, if you there is a mortgage on your home, the lender requires proof of homeowner's insurance.  

Around here (Ohio River Valley), the "risk takers" live in the flood plain.  They often are forced to take this risk bc/ the flood plain is the cheapest place to put a trailer and they can't afford to rent a lot elsewhere.  Theoretically, as flood waters come in, you could just pull your trailer to higher ground.  In reality, most of these trailers cannot safely travel and the occupants do not have access to a vehicle to pull them anyway, especially on short notice.  Many trailers were destroyed in recent floods (the worst being due to the remants of hurricanes Ivan and Frances that came all the way up to Ohio river valley roughly 10 days apart in 9/04).  Local officials have been trying to close down trailer parks in the flood plain or force them to build up the lots but it's hard to enforce as there aren't many alternative locations on flat ground around here that are affordable.

Now, I sometimes ask how is it that they cannot afford a lot outside the flood plain if these trailers all seem to have satellite dishes and the occupants seem to be able to afford a pack or two of cigarettes a day- but that's just my cynical side.