>There's no honest way to resell tokens at a profit, and everyone knows it.

Agree with the sentiment, but I do think there are edge cases.

e.g. I could see a place like openrouter getting away with a tiny fractional markup based on the value they provide in the form of having all providers in one place

The issue with a model like this (fixed small percentage) is that your biggest clients are the most incentivized to move away.

At scale, OpenRouter will instead get you the lower high-volume fees they themselves get from their different providers.