Speculation that it could become worthless understates the situation. It's pretty close to a mathematical certainty. The problem is, obviously, unless you're a criminal, there is no reason to buy Bitcoin other than to gamble that you can sell it for more later. If people stop thinking it will rise, then there is only a reason to sell, and no corresponding reason to buy. Faith in anything is easily eroded--faith in the face of millions of dollars in paper value vanishing before your eyes is especially fragile. The value of Bitcoin is so high, and it has bounced up and down so much that it's not absurd to think it will come back, so hope remains, but that's a finite thing--eventually, a combination of the gradual erosion of faith and market boredom will curtail that hope, and it will fall precipitously as people become convinced it's a death spiral and more and more try to cash out to save a little something. It's impossible to predict precisely when, but it has to happen. My guess is grand implosion will happen when there's a major equities market crash and too many people need cash. It doesn't have to drop to zero to make death certain--it only has to drop past the point where it's not worth mining, which has to be close to the 10k per coin range now! Once the miners are in negative territory, paying more for power than a coin is worth, how long does anyone think they'll keep the lights on? Maybe there'll be some whales with money to burn to keep it going temporarily so they can sell a few more coins to the credulous, but I can't see something so inherently unstable, with such an obvious exponential failure mode built in, lasting indefinitely.