The world can really be a scary place, it is hard to deny. The only thing that can help with fears of extreme events is realistically estimating the probability. There are countless terrifying things one can imagine happening to them, that, unfortunately, not completely outside of the realm of possibility. But if we estimate it realistically, violence or extreme aggression from complete strangers is extremely improbable, to the point where you can essentially tell yourself that it simply is not going to happen to you, because the chance of it happening is negligible.
Getting used to the scary things, if done gently, also helps. When you're in a scary situation for the first time, it can be nerve wrecking, but every time you go out, interact with other people and terrifying things don't happen to you, it gets normal little by little and you get used to the thought that nothing horrible happened last time you did it, and nothing horrible is probably going to happen next time.
