What made Albert Einstein so great (or a genius)?

Yes, you are.
Latin.

Not quite. There is a great quote of Einstein talking to Bohr that goes like this “Do you really believe the moon is not there when you are not looking?” Einstein may have objected to QM absolute randomness; I’ll admit I don’t know. I do know he was bothered by the fact that quantum objects are not in some given state until that is measured. For example, position is a state. If a photon leaves a Quasar somewhere in the deep reaches of space, and there is a “simple” gravitational lens between there and here so that the photon can travel either of two paths, the QM says that the photon is “in a superposition of having traveled both paths”. If you perform an experiment that can determine which path the photon took, instantaneously, the photon “picks” a path, and is in a state of having travelled that path. Bizarre, and Einstein never accepted it.