Coinjoin will reduce the value of your coins. You might be in a circular economy, but it often happens that the recipient refuses coinjoined coins, because they know they will be refused by the exchange.
Also, very few people actually do coinjoin. Most just talk about it. And it is not something that normies would do.
Lightning is actually better for this. But it still is easy to doxx yourself, especially if you mix onchain and lightning.
You are mixing exchange KYC to the issue.
In an economy where Bitcoin is widely accepted, things like coinjoin and other privacy practice will be seen as normal.
As a merchant, rotating your address even once a week will make it very hard for an external observer to tell how much you make in a year. Not all your clients will want to doxx you.
Even without perfect privacy practice, Bitcoin makes your wealth much harder to audit to an external observer.
