Because I'm considering privacy here and not whether or not a coin can become a global payment solution.

If you want bitcoin to become a global payment solution, then it must be done with the tacit approval of governments worldwide. As much as I hate that that is true, that is the situation we find ourselves in. I don't think governments would ever allow an anonymous coin like monero to become a global payment solution, and will only allow it to happen for bitcoin provided they can continue to spy on the vast majority of bitcoin users through centralized exchanges, KYC, blockchain analysis, etc.

Now, if it ever becomes impossible to use bitcoin privately, it will be because governments around the world have shut down every mixer, shut down every P2P marketplace, shut down every merchant who accepts non-KYC payments, and so on. Sure, they can't stop me from owning bitcoin or running a node or buying and selling peer to peer, but they can make it near impossible for me to use it as a currency to buy my groceries or whatever without buying in to their KYC nonsense, and they can use a lot of resources to deanonymize me and monitor my transactions. At that point, bitcoin will have failed in its objective to be a peer to peer currency without any third party intermediaries. And so I'll switch to monero. I don't think monero will never be a global payment solution, but more importantly, I'll be able to use it privately.