1) Bitcoin is not the most saleable good either by your own admission. Fiat is.

2) As much a point against Bitcoin as it is Monero

3) Just an assertion. None of that logically follows. Something becomes more scarce the more it is demanded. Supply alone doesn't dictate scarcity.

4) Unless Bitcoin suddenly stops being a transparent chain (never going to happen) it can't replace Moneros usecase. Different trade offs. L2s come with different disadvantages than blockchains. And a private L2 built on an encrypted blockchain offers unparalleled privacy that Bitcoin can't.

5) This theory conflicts with the real world. Bitcoin had all that going for it on DNMs yet is still being displaced by Monero.

Currently using both Bitcoin and Monero is bartering as neither are the most saleable good the US dollar is (which is why stablecoins are so popular globally). They're both tools with different advantages and most of the world is never going to use them in alignment with their core value props. Most of the world operates on white markets - a central authority dictates what transactions are allowed to take place there. They can ban Bitcoin/Monero there, greatly restrict its usefulness, and tip the tables to advantage their own fiat currency. Bitcoin and Monero don't change that.

They're options we didn't have before to opt out of fiat on parallel economies. Not a replacement for fiat.