I have one of those lists! It's
this one! And that shows the problem: anyone can make up anything about any UTXO.
Oh my god, this explains my following point perfectly! But I will post it anyway, because I have written it already.
Like I said, if someone pays you in BTC that is on some of these lists, and you pay to someone, then this someone puts it on Coinbase (most likely, most mainstream exchange) to sell, and this person gets asked where this money came from, this person will point to you. So yes, this is a huge problem when it comes to fungibility.
No, this isn't a huge problem. Let me ask the obvious question. You say "this person will point to you". Who is this "you"? How will they know it's you?
Let me draw the picture again:
1. takuma sato gets paid 1 BTC.
2. takuma sato sends this 1 BTC to me (apogio).
3. apogio goes to a KYC exchange and deposit this 1 BTC (don't ask why, I just make it more difficult to prove that the scenario is invalid).
4. the KYC asks apogio (the real person behind the persona apogio), where did they get it?
5. apogio says: "I received it from someone with this address bc1q....".
6. then, the authorities (the most strict ones that you can imagine) search on google the address.
7. they (somehow) find that it is linked to a persona called "takuma sato".
8. they search in the forum for other posts and they make sure that "takuma sato" owns this address.
9. then?
Trust me, I am the one who will have a problem. I will be the one to answer the questions for having this Bitcoin. I will face the consequences for deciding to use a KYC exchange. That's all.
Notice, that in this scenario, I didn't add any protection measures from your side, just to make it more clear.
If between steps (1) and (2), takuma sato decided to do some coinjoins, or to just simply add one more address in the route, by sending to address B and then to apogio, then the authorities would have to search who this address B belongs to, before going back to "takuma sato's" address.
It depends, if they are tainted linked to millions of dollars from selling drugs they may bother. You never know who sent you the coins. The problem is evident. They would try to contact theymos I guess, then check logs and so on. But im talking about buying in real life. You buy something in real life, and they will know who you are, even if you don't exchange personal details, you showed your face, there's cameras everywhere nowadays etc. If you don't see a problem of using BTC to pay someone and end up in some sort of investigation about drugs or whatever then I don't know what to tell you. BTC problem when interacting with KYC interfaces is obvious, wether you do it directly or you send the coins to someone and then they do it later on. And if you want to buy anything relevant (real state, diversify in assets etc) you are going to need to go through KYC). And if you want to buy in shops, pay for services etc, you carry yourself a person physically, when you pay you are there paying. This leaks information, and you don't know if your BTC are tainted or not. I don't see how this isn't a problem.