> Economic arguments almost always apply strictly to idealized worlds where each individual calculates the pennies for each action etc. The degree to which such deductions apply to the real world varies.

But the assumption that individuals actually make that calculation is not necessary for economic models to be useful.

For example, players who act in a game theoretically optimal way in some game will, over the long run, dominate and displace players who don't.

This is true even if those players don't actually know any game theory.