Currency failure generally occurs due to the type of hyperinflation, and there is always the potential for technical failure, currency competition, political issues and so on. As the main basic rule, there is no currency that can be considered very safe from failure and difficult times. so is it possible that bitcoin can become worthless?
It can, I mean, you don't have to look that far mate. Many altcoins have already had that fate in this market. Before, especially when they were starting up, they seemed to be on the path of steadily gaining, quite similar to the status of the seasoned coins around the market. But, many of them now are buried in the hundreds of coins competing around the market, with no trace or hope of ever coming back up. There are so many changes that can happen over the course of time, an asset can prosper or even fall down into the depths, thus, that can also happen to Bitcoin, but not at the moment, I guess.