Let’s unpack that. By “crypto” you probably mean cryptocurrency, but let’s not forget it’s the same crypto as in cryptography. You absolutely want cryptography involved in something like this for obvious reasons.
You’ve probably also heard the term blockchain and immediately think of speculative currency futures. So throw that to the wind for a second and imagine how useful a distributed list of records linked and verifiable with cryptographic hash functions would be for this project.
Then finally, run this all in a secure and autonomous way so that under certain conditions the action of releasing the key will happen. In other words: a smart contract.
This is an absolutely perfect use of Ethereum. If you think cryptocurrencies are useless, then consider that projects like this are what give them actual real world use cases.