Your logic only holds true as long as the Miners are the ones holding the largest amounts as they are the ones that can 51% attack bitcoin.
A collusion of just Chinese miners has had more than 51% combined for over 2 years now.

If the Miners decide another coin benefits them more than bitcoin, then they could potentially dump bitcoin and then 51% attack it to destroy it and point to their other coin as the #1 coin gain profit as the non-miners jump to follow their lead.
Things the Miners can do and no one can stop them.
1. Miners could collude to raise the transaction fees to insane rates , users have no options but accept or let their coins sit frozen.
2. Miners could just refuse to add new transactions to blocks , and users are powerless to stop them.
3. All the Miners could just mine another coin and let bitcoin freeze up in a death spiral.

People just holding bitcoin and are not miners are really just minions of the miners , as the miners are the ones with all of the power in a Proof of Work coin as Bitcoin.