How often does the worst-case "WHAT IF" ever materialize? Why worry about something that may never happen? Do you? Because?

I kinda am too. I haven't figured out yet how to turn my brain off. It thinks what it wants to think without my permission. A friend came over for a visit yesterday and we were talking about that very thing . She said it does no good at all to worry because what will happen is going to happen. Of course we were talking about the 2016 American prez election. I know she's right but I still worry. Thank you for your reply MaCC! :)