Very good examples of that are Robert Prector and Harry Dent. They take a reading of the herd mentality then play off it in a sensationalistic manner with exaggerated market predictions consistent with the prevailing mood,all to sell books and subscriptions. How else do you explain their shifting back and forth between euphoric and doomsday predictions. And I bet many of the same who bought their books proclaiming Dow 40000 now buy their books proclaiming Dow 3000, as their mood shifted.
I've never thought much of Robert Prector, as Elliot Wave Theory is far too complex and arbitrary to be useful even as TA.
Harry Dent had a good theory in demographics, but like many theories, it wasn't the most important factor in a changing world. Fed Moneyprinting is the most important factor today, and that will continue until it is discredited and something replaces it, like the Chinese Empire starting in 2017.