You and so many other people in this thread misunderstand how a 51% attack would work in this context. You buy a house, the transaction gets on the blockchain

You and so many other people in this thread misunderstand how a 51% attack would work in this context. You buy a house, the transaction gets on the blockchain network. Just like you wait for confirmations with Bitcoin you'd wait e.g. for 1 day or for 1 week confirmations, this would be agreed upon by both the seller and buyer. Now, let's say someone with deep pockets re-computes the last 1 week of transactions in a 51% attack and "undoes" that transaction. The branch of the blockchain that got replaced doesn't just disappear, it has your house in it, thousands of other houses will have been sold through that branch of the chain, and thousands of people will have that full public record. At this point you and the rest of the owners could obviously go to a court and get your houses back, just as you could if the deeds got lost through a fire today but you had other evidence to prove they existed. Nobody's suggesting that the entire court system be replaced by a blockchain and we ignore all other mitigating evidence, it's just being suggested that storing e.g. deeds in such a system is more reliable than storing them in a couple of filing cabinets somewhere.