There is a common misconception that classical economic models require that everyone be "rational." While everyone being rational is consistent with these models, often a much weaker assumption would do. Here are a couple of examples:

Economics results like the law of one price only require that arbitrage is eliminated. This requires that someone with sufficient means take an opportunity to profit, but is consistent with there being a lot of irrationality.

This is also the case with my unquestionable refutation of time travel. https://twitter.com/KevinZollman/status/1296517935654154246?s=20

Or take the law of demand. It's relationship with rationality is complicated. Everyone can be rational, but the law fails (because people don't have selfish preferences). Also, the law can easily hold even when everyone is irrational.

Finally, there is my area: game theory. While Nash equilibria are often described as the consequence of common knowledge of rationality, this is neither necessary nor sufficient to guarantee that people play the Nash equilibrium.

I think articulating exactly what results depend on what kinds of rationality assumptions would be an incredibly interesting dissertation project. (So if you know of anyone looking for something in this area...)