While I don't think it's inevitable, insurance industry figures claim the average motorist goes seven years between accidents. If it's considered normal for motorists to crash into each other every seven years, it's fairly reasonable to assume we could get hit too.
And this number is not for accidents you're at fault for - it's for any accident. One minor fear for me is waiting at a traffic light and being hit from behind. Over the past 15 years, I've been in a car (twice as driver, once as passenger) hit from behind while stopped for a traffic light, traffic backup, or to make a turn. Two of those times the other driver just wasn't paying attention. One time the driver at least had the excuse that wet leaves make stopping going down a hill harder. All three times it was over $4k in damage. I wonder what kind of damage that sort of collision would cause to a bicyclist.