I shook my head and smiled when I read your reply. Firstly let's start with this;
It wasn't the first successful cryptocurrency; others were as well (in the beginning), but they failed due to centralization and all the problems that come with it.
Here you are actually contradicting your self by saying it was successful and later failed because If it failed in the first place then it obviously wasn't successful. From you point of view you are literally saying that any coin or project that was launched is a successful project. Take BitConnect (BCC)
Launched in 2016, and later became worthless in just a couple of months, would you call that successful?
Now for this part of your reply;
It was not a cryptographic breakthrough; it was a novel concept called "Proof of Work" to address the double-spending problem.
The cryptography behind Bitcoin was well known, but the way it was used was a breakthrough.
Before bitcoin, there was no successful coin that made use of cryptography you are also simply contradicting yourself here because both Proof of Work (
POW) and Proof of stake (
POS) are crypto graphic terms because they are applied in Cryptography. If bitcoin wasn't a breakthrough as the first successful crypto currency then what will you call it?