Exactly, and which chain to miners follow? The one which has demand for coins.
And which coins are in demand? Those which can be traded for something other than bitcoin.
And who decides what fork is valid bitcoin? Those who have something to trade for it.
Read my original comment that you disagreed with more carefully.
Anyone can fork bitcoin and many have. Nobody is stopping a fork and nobody needs to follow that fork. My node enforces the rules of the network I want. Miners will mine the most economically viable fork. All the interests align. The most economically efficient version wins. Miners don't mine out of charity and node runners don't run nodes that don't align with their interest.
Correct.
