Unfortunately, the useful part is not new and the new part is not useful.

Blockchain

The useful-but-not-new part is that its data structure is a Merkle tree - something you know already, it's like git.

The new-but-not-useful part is that it has a decentralized consensus algorithm. Technically, it's impressive, but it is also very complex, which means for whatever thing "you can do with the blockchain", there is a simpler - therefore better - technical way to do it. Therefore, in most cases the blockchain is "needed" not technically but for ideological tech-bro libertarian reasons.

Bitcoin

Likewise, Bitcoin is new and that is mistaken with being useful.

You have story-telling from the tech-bro who have invested early in Bitcoin and got rich. That's the ultimate proof it must be good right? Nope. It was a good investment precisely because it's a bad currency. A good currency needs stability. The value of your savings never lose 20% just because Elon Musk said mean things about the euro or the dollar.

There are lots of people who wants to get rich by doing shady and/or illegal things.

Bitcoin's killer feature is that police is police, and the banks and the democratic institutions are relatively powerless to go after those guys.

• Bitcoin is good for non-regulated internet gambling
• Bitcoin is good to sell arms and drugs
• Bitcoin is good for obtaining ransom

A personal story

Two weeks ago, my wallet was stolen in Paris, and the thieves took 5,500 euros from my bank account.

When something like this happens - and it happens all the time - with bitcoin, that's the end of the story. Too bad for you, you lost your money, you are on your own.

But there I had a centralized institution called "the police" where I said my money was stolen. And just like that, a centralized institution called "my bank" gave me money back. Because a centralized institution called "the government" forces it legally to do so.

Don't buy the libertarian ideology that centralized institutions must be thrown away with the bath water.

Recommended reading

I only scratched the surface, didn't evoke the gigantic waste that Bitcoin's proof-of-work causes, but if you want to know more, I promise you will find those articles interesting:

• Ten years in, nobody has come up with a use for blockchain | Hacker Noon
• Blockchain is not only crappy technology but a bad vision for the future | by Kai Stinchcombe | Medium
• Why Cryptocurrency Is A Giant Fraud ❧ Current Affairs