Earlier quoted context omitted.
It won't if people realize that BTC is not a useful product, and the price falls to $1k or $100. At that point no one except someone stealing electricity can afford to mine, so the entire monetary system collapses and becomes worth the same as US Civil War dollars (can maybe buy a loaf of bread with a wheelbarrow full?)
Given that bitcoin has been around for 2008, at what point will you personally concede that it's not likely to happen? Why would it happen now if it didn't in the first 13 years?
Given the increasing prevalence of ransomeware attacks, and the fact that they have touched higher and higher profile targets, it's not impossible to imagine the regulatory hammer coming down on cryptocurrency at some point in the near-ish future.