I wouldn't say it's worthless per se, if there's people willing to transfer it into actual cash or items then it couldn't possibly be. There are plenty of vendors online that will let you buy stuff with bitcoins and even tales of people buying houses with them. It's not so much a digital currency as it is stock, sometimes the price increases and people want to get into that so then they start mining for themselves.
I would say at this point that bitcoin is so overpriced it's loosing it's value though, since no one in their right mind, hopefully, would buy a coin for 1000+.
I remember learning in History that in America people were very opposed to the idea of having paper money because instead of having some precious metal in their pockets, they had something that symbolized it in paper form. I think it's sorta the same way now with people. People don't want "fake digital money" because it's something that symbolizes value. (Even though that's all that money in itself is anyways, if you think about it. )