Born came up with his probability interpretation of quantum mechanics. But why did he think about such an interoretation? Why not thinking that a deterministic process has to lay at its foundation? All known processes were known to be fundamentally deterministic. A dice thrown, the motion of the stars, the motions of atoms in a macroscopic gas, etc. Why did he think that the processes in QM are inherently probabilistic? A notion hard to digest (you can say QM is hard to digest but this begs the question).