Offline users do not know which one is the main chain.
Ostensibly you presume that COINBASE et al are going to agree with what the users who were live thought they observed.
It cant be proven that one live groups network synchrony was superior to another group's.
The point is you are presuming objectivity where objectivity doesn't exist.
I am presuming that you have to ascribe game theory. Regardless of whether or not objectivity exists, there will be a loss to those attacking the network (and to those actively defending if the attacking network persists). Unless 100% of all economic value goes to their fork, they suffer a loss. Even if they convince 90% of the economic value to move, they lose the 10% which remains on the other fork where their stake is destroyed. Only the non-staking users of the network do not lose any value.
I know you do not believe in fairytales so why would you believe the world is some fantasy fairytale where corporations and gatekeepers do the moral thing so they can lower their profits?
See above.
And their motive may not be double-spending but rather censoring transactions
If that is the case, the objectively better fork is obvious.
Also for a competing token to their Bitcoin, maybe they just want to destroy your token and short it into the ground.
But to do so they have to invest in the network itself, unlike with PoW. They must hedge that not only can they destroy your network, but that they can get you to believe it is destroyed.
The powers-that-be get their power largely through manipulation.
But I trust my grandmother more than I trust CNN, or Coinbase, or the government. She runs a full node. Plus, the decentralization of currency should at its core help decentralize society as a whole and reduce the power of governments and megacorps. Maybe. But if it doesn't do that, it's probably not the fault of crypto but people. However, it'll help once cryptos start appearing that decentralize the creation and distribution of new money so that there is far less competition for stupid one-feature wonders promising $$$billions$$$ as you mentioned elsewhere.