I'm not saying that after four serious accidents that I wouldn't also give up cycling... after one serious accident I gave up motorcycles... however, I do not blame anyone else for my misfortunes. I do not see where the o.p. owns their part (and they do have one) in the outcomes of their accidents. It is my firm conviction that there are other cyclists riding completely accident free commutes or other kinds of public riding in the very city, the very same neighborhood even, that the o.p. lives in. Four accidents is three too many. Giving up cycling is probably the best decision, but to make it seem like a decision forced by the actions of hostile, antagonistic, unthinking, unfeeling drivers. I don't know... seems a bit much. Here's what I would do... I would go to a local bike store and see if there is anyone there I could shadow. Maybe join a local club, prolly they mostly ride on weekends only, but you might find some hardcore commuters in there... whatever, you find yourself a streetrider who is not having as hard a time of it as you are and see how they go about staying in one piece out there. FWIW.