But there isn't any useful new technology.

The only new technology there is the consensus part - the wildly expensive part where all the nodes agree periodically on the state of the world, and attempt to mitigate the unsolvable Byzantine Consensus problem.

But this step is only useful if you are creating a completely trustless transaction system with no sources of truth at all. And it turns out that, aside from cryptocurrencies themselves, there is no actually application to this.

You're like, wait, what about my distributed ledgers? What about my certificates of authenticity?

Turns out that all of that could be done with vintage technology without a blockchain for a tiny fraction of 1% of the cost of this huge consensus step.

We've had strong cryptography, digital signatures and immutable distributed ledgers since the late 1970s!

What the blockchain adds is this consensus step which in any real world application, real estate, ticket sales, sales of merchandise online, medical records, you name it, this consensus step makes everything infinitely slower and much more expensive and prevents you from doing a lot of things that in practice you need to do, such as responding to crimes, legal action or simple mistakes by changing the ledger - actions that can be done in a controlled and documented fashion without this ridiculous blockchain, but with a blockchain require the travesty of a hard fork.

It's all a scam. Sell now. :-D