They are right about high valuations in general. Their conclusion is just looking back and assuming future is same as before, with little to no reasining. Wha

They are right about high valuations in general. Their conclusion is just looking back and assuming future is same as before, with little to no reasining. What very high valuations mean is lower ROI in the future, only that. I'm 99% certain that Total Return (TR) from stock markets 2010-2020 >> 2021-2030. SP500 TR is 13.97% annualized for last 10 years (price return 11.64%). I'm surprised if it's above 5% annualized for next 10 years. That does not necessarily mean rapid decline in valuations (as bursting or crash). It can be stagnated stock market. It can be market boom that continues next 5 years and then fall back little above 2020 levels.