Certainly agree with you Matt.   I believe the biggest contributing factor to what you've said is that younger investors haven't ever experienced a real major decline.....like say 57% in 2008.    If you invest in stocks, they will always go up....guaranteed......therefore they have no fear.   Any small declines will eventually be consumed by buying......no doubt about it in their minds.   I'm thinking a major major crisis will occur at some point taking everyone by surprise....could be a year or years out, but massive stimulus and government debt to GDP will eventually bring things down.  It only will take some catalyst that no one expects.   When looking at a monthly chart going back, say 30 years, all one has to do is draw a trend line to see how parabolic things have been for the last 15 years, and in particular the last 6 1/2 years.    All in my humble opinion.