Protocol/code is law. Having UTXOs with different history has no implications of how it is spent on the protocol. Thats what matters. You can put all the goofy identifiers like “omg this was owned by this KYCd person”! But doesn’t change how it is spent or how the protocol receives it. When everyone is dead in 200 years and they find kyc bitcoin do you think they are just going to toss it aside and say “that’s not bitcoin it was KYC’d 200 years ago, toss it in the “fungibility grave yard”. Nah they are going to spend that shit like any other coin. A UTXO has a unique identifier, yes, I don’t see how this makes it any less valuable or interchangable than another UTXO with the same amount that is nonKyc. Increase your time preference and see how nonsensical this is.
1 BTC = 1 BTC on a protocol level, not in the real world. You have to make one Bitcoin technically indistinguishable from another to achieve that. And it can't because it is a public blockchain and they each have unique histories.
As chain analysis services and tools become more sophisticated, accessible, and easier to use, and regulations increasingly clamp down, all those businesses will be forced to be more choosy to save their own asses. You already see this with KYC/AML laws. Automatically assumed guilty if you can't prove the history/source of your money.
We will see a bifurcation of black/white market bitcoin at different premiums/discounts based on history. There are already examples of this: https://sethforprivacy.com/posts/fungibility-graveyard/#compliant-mining-and-virgin-bitcoin
Of course, this won't matter as much for gray and black markets, but will still matter to some degree.
I'm saying this as someone who also holds Bitcoin.
Discussion
Not to say people won’t pay a small premium for acquiring privately, but saying that it’s not fungible is ridiculous
It's more that white markets won't want to deal with the risk of tainted funds because of increasing regulation. Tainted coins might not be accepted or undervalued at other places for the same reasons. So businesses and people will either refuse them and ask for coins with "clean" histories. Or they will accept them for a discount.
I think Bitcoin/Monero were always meant to be black/gray market money.
I just feel more cynical about it and don't see how this isn't the outcome. But I rather have what you are saying be true.
Like I said earlier in this chain I truly respect the privacy ethos on the infosec coiners. But I also have to look at “who benefits the most from this rhetoric?” Which is obviously the privacy coin holders who would love to benefit off of Bitcoin’s downfall. I guess I’m just cynical in a different regard.
That said, what you’re saying is not entirely baseless shit can get pretty whacky in the next 10-20 years as governments come to terms with losing printing power of currency which is why we’re having this discussion. I think everyone wants to improve Bitcoins privacy and find a quick solution like “this coin does this!”. L2s are going to improve, and users aren’t going to know the difference between kyc/nonkyc in 20 years bc it won’t matter.
I'm not saying Monero would be accepted on white markets. But whether it is or isn't, doesn't effect it's fungibility, unlike Bitcoin. Monero must either all be accepted, or all be banned, because each monero is indistinguishable. There is no historical transaction graph. It can't be bifurcated into clean and tainted Monero based on history.