The exact timing is always tricky but I have seen the .COM bubble and the 2008 crash. In both it was pretty clear that the economy was in a huge speculative bubble that made no rational sense but the bubble was prolonged until there was no way forward anymore. The 2001 crash was bad, the 2008 crash worse and I think this one will be even bigger. We ran up huge deficits during good times, kept interest rates artificially low to keep things going. And most of the superstar businesses (unicorns) don't even know how to be a business that makes profits.