Most likely the low probability for Bitcoin value to be zero. That's because Bitcoin is naturally volatile and only risky. Altcoin can never replace Bitcoin because it is not independent. The exchange of altcoin prices depends on Bitcoin, it means that, its value is directly proportional to the value of Bitcoin. In addition people do not give importance to this system and create some negative issues or topics that can cause the system to crash and push it to the end. And even I have heard a lot of negative speculation, confidence and confidence.