[mettamage]

I second this. Blockchain is still an amazing technology though. I think the general concept is even way cooler (blockchain is, I think, an implementation detail).

The concept is: decentralized databases

When should you have that? Well, one example: whenever you need a database, and a centralized database is politically or socially impossible.

Fun fact: bitcoin is a better currency than any currency that is undergoing hyperinflation right now. Some of those places also can't have centralized databases.