Note that the property we're talking about isn't really irreversibility of individual transactions. We can come up with whatever policy about what can show up in a ledger, including "undo" transactions.

But what we want is that once transactions are recorded to a ledger, that it's not possible to remove that record.

This durability is a highly valuable property for financial transactions and other things where non-repudiation is desired. However, it's a possibly scary property, too (what if something copyrighted or illegal ends up in the forever-durable and public ledger?)

That criticism also applies to cash.

True, although most people wouldn't hold nearly as much cash as is commonly held in bitcoin.

I guess wallets are called wallets for a reason.

You'd keep in yourself a small amount of Bitcoin. You'd keep at home a bigger amount. You'd keep in a safe place the rest. Exactly as with cash.

You put cash in a bank.

You can put your seed words in a bank safety deposit box.

Safety deposit boxes turn out not to be secure or guaranteed. https://www.bloomberg.com/opinion/articles/2019-07-22/don-t-...

It depends on the country but I agree. Being programmable money I expect better solutions to come in the future. This is a recent and interesting one https://blog.trezor.io/shamir-backup-the-revolution-of-priva...

> Based on a cryptographic algorithm created by Adi Shamir, publicly known as Shamir’s Secret Sharing, Shamir Backup is a revolution in how you use, store, and protect the backup of your private keys.

A "revolution". They just applied SSS. Hardly rocket science.