You are right. It has failed as a currency and as medium of exchange but as a store of value is a huge success.

You can measure about anything you want in $ but that doesn't mean it is denominated in $. The Mona Lisa cost a lot of $ but that doesn't make the $ more important or useful. It's just a habit. Soon, people will start denominating expensive stuff in BTC; this house costs 10 BTC and the like, but that doesn't say anything about the currency.

The FBI, the CIA, The FED had been hacked at some point. Centralized entities are very vulnerable, even powerful ones. Decentralized systems are much harder to penetrate because there is nothing to hack. Only a 51% attack would cause some problems but even that is higly unlikely. If it hasn't happened in 12 years despite everybody trying, the chances of happening in the future are almost 0. Besides, now is too big too fail