Because of some physics-y thing or something, scientifically speaking, there is an alternate universe that is created by each and every one of the choices anyone makes (universes where they chose something else pop up), this is actually quite possible somewhere out there.
The theory of bubble universes really puts anything fictional or a dream you've had into reality basically, different versions of you or a way of living could be real in there universe. If the theory is legit its not far fetch to say Harry Potter is real and in his universe we could be the book or show. This thought keeps me awake at night constantly by the way.
And Harry, Ron and Hermione were reading books about OUR lives!
---
DFTBA<3