In this video the use of private, personally identifiable information is used by bad actors to access databases of intelligence agencies. While I found the entire discussion relevant and fascinating, the upshot is discussed by Jack Rhysider after ~1:10:00, so if you want to cut to the chase, to the crux of why biometric ID is utterly intolerable in a world in which malicious actors can use it to profit from your identity AS LONG AS YOU LIVE, start there. In fact, your biometric data may well be usable long after you're dead, as elections today seem to prove. Note: I don't think the word biometric is even used in this video. However, it is blatantly obvious that as bad as the security risks already are, adding your biometric data that you can never, ever change, will make every risk infinitely worse.
The simplest and most fundamental takeaway here relevant to every single human being on Earth is that in a world in which evil exists, using biometric data that you cannot ever change can turn you into a vector for criminal activity that can not ever be dissociated from your person, and using biometric data for ID will inevitably be used in that way, because not even the most powerful intelligence agencies on Earth can prevent literal script kiddies from hacking them.
It also demonstrates just how easy it is to eliminate cryptocurrency as a store of value and means of transaction, and utterly refutes any and every claim it can ever be money. It's just data. It can never, ever be secure from even the simplest forms of censorship. I've read estimates that ~1/6 of BTC is simply unable to be accessed ever again, because the keys are lost. I've lost a lot of hard drives since the 1980s. All that information is gone forever, at least to me. It exists somewhere in the multiverse, because information cannot be lost once it exists, but it sure can be lost to me.
We are made of meat. What we can secure and use may involve information, but if it isn't made of actual matter we meatbags can just lose it, like we lose track of our tears in rain. In a real sense our value exists in relation to them we love, and who love us, and that is all that really has any value to us. We have a vastly better chance of retaining possession and access to things made of matter than pure data. It doesn't actually matter to meat puppets that the universe can't ever lose data, because we are not the universe. We're bags of obscene glop, and are designed to function in relation to other bags of glop and material stuff like plasma, rocks, and gases. Data is rather esoteric at this level of consideration.
Once you lose access to it, whether it's your keys or your biometric details, you can never put it back in your vault. I hope only to encourage everyone to keep this in mind always, so you are less likely to be harmed in the infinite number of ways meat sacks can suffer from becoming dependent on data that can be permanently taken from you by circumstances beyond your control. Humility, recognizing we are hunks of meat, lucky to be able to tie our shoes in a universe of more information and complexity we could even conceive of, is the best rational practice, the foundation of such feeble wisdom humanity is capable of.
If it can be taken from you, it was never really yours. Stay frosty.