So "rational choice theory" is a misleading misnomer. It should be called "rational choice principle." A scientific theory is a model, perhaps based on unfalsifiable principles, that's nevertheless been established by tests that could have gone the other way. Scientific theories include principles or axioms (definitions or equations) and empirical hypotheses and testable predictions. Without that testing, the principles are comparable to theological creeds.

Here, then, we have a concrete case of pseudoscience in economics. It's called "rational choice theory" to make the principles seem scientifically grounded, whereas by themselves they're a priori dogmas.

Here's a summary, though, of rational choice theory's role in economics (link below):

"Rational choice theory states that individuals use rational calculations to make rational choices and achieve outcomes that are aligned with their own personal objectives. These results are also associated with maximizing an individual's self-interest. Using rational choice theory is expected to result in outcomes that provide people with the greatest benefit and satisfaction, given the limited option they have available."

Now does that sound definitional or empirical to you? When put in ordinary language like that, rational choice theory seems perfectly empirical and falsifiable. It's just that the key terms in those assumptions are defined to make them trivial and unfalsifiable.

So there's equivocation going on here, a rhetorical game. Sometimes the economist's basic assumptions about rational choice are empirical and sometimes they're not. It depends on the audience, and the goal isn't to get at the truth but to protect the institutions and pride of economics.

https://www.investopedia.com/terms/r/rational-choice-theory.asp