I'm not a pessimist, I'm a realist, if one was trying to buy travel insurance and the insurance company asked me how I was travelling and I told them hitch hiking, do you think they'd insure me ?
Have you noticed that all pessimists term themselves realists? If you leave it to pessimists, there are no pessimists.
And this pessimist should note that none of the several annual travel insurance policies I've bought in the last ten years have even bothered to ask questions about how I intend to travel. and have certainly not attempted to exclude for cover any means of travel including hitchhiking. These Insurers plainly don't have evidence to the extent that hitching is more risky than other forms of travel.