I don’t agree the axiom of action is self-evidently true, because it presupposes the existence of libertarian free will, which I also don’t think is self-evidently true. It’s certainly incompatible with any naturalist position. But we don’t need to go down a metaphysical rabbit-hole to find problems with the axiom.

While it’s true that the subjective theory of value and marginal utility come out of the Austrian School, it’s worth mentioning these things are accepted in mainstream economics today. A lot of Austrians seem to try and play a sleight-of-hand where they suggest that because these things are accepted, the full corpus of Austrian School thinking must also be true. This is obviously logically fallacious.

Furthermore, the axiom of human action implies what is known in philosophy as psychological realism, which casts aside problems of environmental factors, social contexts, cognitive biases, and any discussion of emergent social behaviors. In fact, to even bring up that last point will often get an Austrian screaming at you that you are introducing “collectivism” by even going down that route, which is apparently self-evidently evil. So you’re already into a realm where we’re not even talking about analytical economics anymore, we’re deep into political ethics before we even get off the ground.

This is why most Austrians are either libertarians or anarcho-capitalists. They believe there is an objective reality, founded in Austrian reasoning, that proves that these political philosophies are necessarily and obviously the most ethical systems. It goes without saying, I think this is absurd.