They are competing with Bitcoin whether they like it or not. CBDCs are a result of Bitcoin applying pressure to central banks. As long as the money offered by central banks is censorable and heavily debased, they will be in this battle.

And no, they can't destroy something that can be forked and updated an infinite number of times. Not sure why you don't understand that its trivially easy to copy Bitcoin and build an alt. As long as that is the case, Bitcoin cannot be defeated.

If the current POW mechanism is repeatedly attacked and defeated it will adapt or projects will move to another consensus method. This is an arms race that CBs cannot win and they will burn a lot of money in process of losing, which is a beautiful thing.

Realize a successful 51% attack is just the beginning of the war, not the end of it.

*All the arguments you put forth so far are defeated by this simple flip of a consensus mechanism switch.