As an amateur philologist, I understand that a language’s fixed idioms survive the conditions in which they arose, and become absurd, if not taken metaphorically. For instance, it is neither uncommon nor incorrect to say that a modern ship with no sails has “set sail”.
“Wallet” is a fine word. It derives from an earlier form of the same word, meaning a ‘bag’ or a ‘pouch’; indeed, if you read old books even in modern English, you can find usages of “wallet” in such archaic senses.
Its crypto-usage grew organically amongst early Bitcoiners. It has the advantages of familiarity and of metaphorical meaning; cf. the desktop metaphor. It lacks the stilted, forced, self-conscious quality of an unnecessary neologism. Although I am not categorically opposed to neologisms, I prescribe that they should be avoided when unnecessary.
To speak of a “cryptocurrency wallet” is no more incorrect than to say that the RMS Titanic set sail for its fatal maiden voyage on 10 April 1912. For that matter, it is no more incorrect than to refer to UTXOs as “coins” or Zcash shielded notes as “notes”.
On the other hand, I agree with this:
And it is one which most people will never understand. (Never mind zero-knowledge proofs!)
Without wishing to incite any mystical thinking, I suggest that the only explanations that could facilitate practical mass-usage are magical metaphors. Magical and mystical beliefs arise organically when people are faced with phenomena which they do not understand scientifically. Such psychology is an unalterable fact of human nature; here, it can be exploited rationally for the greater good.
The Magical Doctrine of Crypto
You have a magic number. You must keep it secret. As long as you keep your magic number secret, your money is protected by impenetrably strong magic. Invincible magic! If you fail to keep your magic number secret, then invisible “blackhat” evil spirits will take away your money.
If you yourself lose your magic number, then you will lose your money. To protect against this, use the standard magical transformation* of your magic number into secret magic words—sometimes confusingly called a “mnemonic seed phrase”. Store your secret magic words with secure physical backups, not on a computer—and keep them secret!
Wizards offer advice about how to protect your secret magic words.
(Image credit: Jameson Lopp. I am not recommending that specific product; I just hunted around for a suitable exemplary image.)
Beware: Tricksters known as “phishers” and “social engineers” will sometimes try to beguile, confuse, seduce, or otherwise scam you into revealing your secret magic number or magic words. Don’t tell them your magical secrets!
That is a practical explanation. It communicates all that 99% of people need to know. And anyone in the world can understand it!
I have previously used magic to explain the Bitcoin mining process. nullius, 2017-12-15:
I add that each magical security stamp (a.k.a. “blockhash”) is magically bonded to all previous magical security stamps.
/me secretly loves magic.
* A note to pedants: I understand perfectly well that the transformation works in the opposite direction: BIP 39 casts its magic words through 2048 iterations of the “PBKDF2-HMAC-SHA512” spell into the magic number input to BIP 32 (or ZIP 32). Hypercorrections of my magical explanations would be unnecessary and unwelcome.