Some insurance companies do charge more and even deny coverage for high risk activities. I am an active motorcycle person that occasionally competes at a low level. It is pretty standard operating procedure to cut your leathers off BEFORE you go to the emergency room just to make sure. I have numerous racer friends that have had some pretty nasty injuries from falling off of a curb "just walking down the street".
And many injurys could happen when falling off your roof when cleaning gutters, taring a chimney or whatever. Might not get so many dumb looks as a I feel off a 6 inch curb.