There is an entire area of math about the uncertainty of decision correctness in incomplete information scenarios. One of the neat aspects of it is that all computable optimal decision makers are mechanically exploitable if you have a reasonably accurate model of their finiteness. In the case of human minds, that just means they are a lot like you. The exploits require iterated games and are cognitively difficult (you have to track a lot of state).
Anecdotally, in my poker playing days I had a lot of success by attacking quasi-optimal play this way. Optimality is contextual. You can engineer a context that motivates suboptimal decisions in fact, though it isn’t easy.
However, at the limit, this is really just attacking the cognitive facilities of your opponents rather than the math of the game. Someone that with a similar ability to manipulate large amounts of state mentally could nullify the advantage. It is meta-games all the way down.
> Optimality is contextual. You can engineer a context that motivates suboptimal decisions in fact, though it isn’t easy.
I agree with your post but I'd just like to nitpick that this first phrase is not true, the equilibrium point is independent of what your opponent does. I'm pretty sure you know this as you then go on to describe not a context where the equilibrium changes but where it becomes hard for humans to find the equilibrium.
So we agree, it's just a small nitpick of how you worded.