After looking again at that long term chart, it LOOKS like the Dow was topping 2015 2016 and to mid 2017. Dines I think was even talking about that topping.
Trump entered the scene campaigning that summer 2017 and he may have DELAYED a natural correction with all that positive attitude about the future. So this correction may have a lot of down side catching up to do. And be real bad. Placebo effect, that hid the “pain” could be wearing off.
Gold tends to go opposite the Dow.