I know it does not resonate to talk about crashes when the market is well and truly in bull phase. But look at the chart link below and you can see that the downturn from the dot.com crash actually began 1 year plus before recession happened. And perhaps a tech stock implosion in US may well trigger the bursting of the tech bubble. Since the bottom of the GFC, DJIA has now climbed a whopping 237% without a major market crash - the last 2 occasions we saw a 59% rise from bottom following dot com crash to pre-GFC highs, and 48% from bottom of 1998 crash to pre-dot com crash highs. So thanks to the Fed, this has been the biggest party ever in Wall St history , which therefore could make it potentially the worst nightmare for markets when we next see the next crisis of confidence. And in the Table below, you can see how long it takes for a recovery after each crash episodes.
As it is commonly said "A Failure to Plan is a Plan for Failure"