Will bitcoin eventually rise or it will fail and reach a value of zero dollars?
There is no chance of lowering of prices. but if you are a smart investor, then you should keep an eye on the fluctuation of prices.
I think bitcoin will not reach a zero dollar for a couple next years, but no one know the future.
Just follow the trend and do technical analysis is the best way to predict bitcoin price.
Hopefully this won't happen next couple of years , I think bitcoin will remain on its unstable price, it will just decrease if something bad happen with bitcoins or people will not use it anymore. But you are right just keep with the flow and do some research.