You switch cause and effect, realism tries to describe the word as is and not as it should be and then bases policies on that.
It's less of a linear relationship and more of a feedback loop. The more politicians buy into this political theory, the more effect it has on the world and vice versa.
yet the world is still made up of poker chips and superpowers.
Iran is a good example of being neither. There are also a bunch of non-state actors who challenge the status quo. Realism fails to explain Al Qaeda, Taliban and ISIS joining the poker table.
Commercial actors are also become more and more powerful and their interests often do not align with those of the state. Google and Meta have a higher revenue than several countries and is capable of influencing public opinion.
Realism fails to explain how all superpowers fall apart from within or from outside forces eventually. Where is the British Empire? Where is the Dutch Empire? Where are the Romans?
Of course the policies you choose based on realist principles can be used to increase your power as a country
It can also be used to lose your power, destroy your credibility and sabotage your economy. Realism also doesn't take soft power into account. You can easily trade your soft power for hard power but it is very difficult to get soft power back.
(given the limitations of the natural anarchic state of international politics).
But international politics are governed by international law and various treaties. Just because some countries can break international law and get away with it, doesn't mean that the law itself is meaningless.
As a Dutch person I accept that the US can decide to turn the Netherlands into a nuclear testing ground whenever it wants and there is nothing we can do about that, but given this fact we should still try to create a peaceful world.
You can do a lot about it, from petitioning other governments to cease diplomatic relations to terrorism. Even a small country, like the Netherlands, is a complex social system with it's own interests and guiding principles and not just a chip in political games of giants.