Someone's sent you a billion dollars in Monero the IRS doesn't know you have - okay. But now when you use it to buy a mansion, won't that be obvious?
Privacy is important to people, and that even extends to privacy from your government. You never know when your government might change from a responsible, fair entity, to a oppressive regime.
If you do buy a mansion with unreported billions and you're buying from a reputable buyer, then you'd expect the government to know about that sale, but if you're stock piling assets in case you need to flee from your government to survive, having anonymous money that's easy to transport is valuable.
> You never know when your government might change from a responsible, fair entity, to a oppressive regime.
Truer words were never spoken. It is hard to get this across to people with the completely understandable "I didn't do anything wrong so nothing can happen to me" attitude.
As Beria said, "Show me the man and I'll find you the crime"...