I remember reading DeBrogli’s thesis when I was younger. In that time, he never thought that his wave function was a probabilistic one. He changed his mind and then back again to a real wave function later in his life. I do not buy the probability function either. It is explaining a few things but it is also putting a break on real advances. Maybe the ‘real’ wave function is also a bad approach but, at least, it is leading to new ways of observing because it is making us realize that we need to look at the world differently.
In a sea of interpretations of quantum weirdness, QBism swims alone. The traditional “Copenhagen interpretation” treats the observer as somehow standing outside of nature, imbued with mysterious wave-function-collapsing powers, governed by laws of physics that are different from those that govern what’s being observed.
www.quantamagazine.org/quantum-bayesianism-explained-by-its-founder-20150604/