I think the problem is that economics needs to take human behavior into account, which it tries to do via game theory, which in turn relies on rational actors. I don't think individual human behavior is predictable like that. You could argue that we don't need to model individuals, only large groups of people. But the problem is that often the behavior of some individuals has a huge effect on large groups.

Contrast that to physics, where we have been very successful with predicting the behavior of masses both on small and on large scale, with relatively few exceptions.

You are on to something with ”behaviour”, ”actors”, and ”rational” . Ludwig von Mises defined ”rational” as ”aiming to an end, using means”. That means that even someone performing a dance to produce rain is a rational actor. He formulated the axiom that ”humans act”. And then derived his theory from that. The science is named Praxeology. A big difference from the natural sciences is that you really can't falsify a theory using empirics. There is no way to repeat an experiment, because reality has been reconfigured. Therefore axiomatic theory is what you have to rely on. Which is not too bad. After all sciences like geometry also make do without empiricism. (There is no way to empirically disprove that a triangle has an angle sum of 180 degrees.)

No, it can't be a science like physics. It is a science anyway. Just not like physics.

It's actually the opposite. Lots of economists (maybe overzealously) discard any statement that doesn't have a model behind it.