Bitcoin will never fail because it's main purpose is just an alternative currency, a decentralized one.
The failure is on the part of the human, either we fail to invest,(we loss) or we failed to adopt on bitcoin, because bitcoin will continue to exist regardless of its price and the number of people using it, which we would never know, and as long as there are miners, bitcoin will live.
If it has failed or not will depend on what the original intent was. It can still exist and even have value even if it is considered a failure.
The most complaintes I hear about the usage of Bitcoin is that it's ;
* Slow to confirm.
* Relatively expensive, especially if paying low amounts.
* Very few shops/businesses accept BTC.
* Hardly anyone use it on a daily basis.
* It fluctuates to much on a weekly and monthly basis
And this is after 10 years of its inception, seems like the majority has given up on it's original ideas and regular Joe can't be bothered.
Well, then I ask you guys this. What if anything can fix this in your opinion?? How would you fix Bitcoin??