Just like Monero - gold has it's own advantages that Bitcoin doesn't and vice versa - like not being reliant on a complex network to use and exist and being fungible and private. It also has several millenia proven history as a SoV vs Bitcoin's ~15 years.
It's not just math its subjective value. Bitcoin can control the supply side of the equation, but never the fickle demand side. That is a constantly changing market process.
Agree that you can just cross swap between Monero and Bitcoin, but comparing it to coinjoins is apples and oranges. Coinjoin is weak privacy via obfuscation. Nothing is hidden. You can see everything. So that means deobfuscation is possible (and even happens to DNM OGs a decade later) with more data or future user mistakes. While Monero amounts and addresses aren't available on it's blockchain. No transaction graph is visible either.
Lightning receiver privacy is weak and unannounced channel amounts can be derived by a sophisticated adversary. Any privacy on L2s always give up main value props of Bitcoin like self-custody, permissionlessness, p2p, final settlement, etc. Ecash for example (probably the strongest privacy contender) is custodial and mints can arbitrarily print unbacked tokens without anyone knowing. None are full replacements for Monero.
Monero is FOSS. That's all that matters. At any moment anyone can sell or swap their Monero if they don't agree with the path it takes and no one can stop them. They can opt out. The community can also fork Monero and no one can stop them.
It's great both expirements can exist and I think they occupy different realms. Bitcoin is trying to be a SoV a digital commodity, while Monero is trying to be the best MoE a digital cash.
