It takes a lot of humility and courage to write such a candid post on something that was obviously the foundation of your hopes for two years. I have great respect for that.
Was it a complete failure? Absolutely not. You've picked up a great amount of technical expertise in the process. More importantly after all this is in the past you'll be able to reflect on it objectively and realise your mistakes and shortcomings - and you'll know, unemotionally, that they were to do on the marketing side.
Rob Walling said something once that stuck with me ever since. If you're looking to build something, approach it in order of "market, marketing, aesthetics, functionality." Not to paint with a broad brush, but it will at least help you realign your focus next time you jump into something like this.
Because you will jump into something like this again.