Majority hashrate + original blockchain = Bitcoin
Majority can only be economic
Economic majority doesn't mean shit unless they put their money where their mouths are and start mining. You could have 90% of all BTC and
be completely unable to stop a hardfork because it's secured by proof of work, not proof of stake. And it's the hashrate that gives users the ability to trust the network. A minority fork is worthless because it's easily subject to a 51% attack giving users no reason to trust it
You didn't answer my question
Namely, what's the purpose of mining a coin which no one is going to use? Look, you tell about 51% attack which is possible due to aggregating enough hash power in a few hands but you fail to see how this entirely nullifies your own claim that hash rate is giving users "the ability to trust the network". What trust are you talking about if all hash rate is accumulated in a pair of hands? It is not hash rate itself that matters, it is its proper distribution that secures the network (read decentralization). Further, if I had 90% of all coins, I could easily sell your fork into oblivion
You assume no one will follow but
https://coin.dance/blocks shows there's plenty of miners who support big blocks and would gladly follow this fork. It's not a binary outcome either, there will be both users and hashrate moving over. And it uses the existing blockchain so all current users already have a stake in this UAHF.
Both distribution of hashrate and brute hashrate matter when it comes to trusting the network. A coin that's SHA256 based is easily attacked if it hasn't got sufficient hashrate to fend off established miners from other networks with significantly higher hashrates. And if you sell your 90% hypothetical stake of coins all you're doing is redistributing them and altering a price, this has zero effect on the direction of the protocol.