That's just the way many short term traders talk about markets and how they perceive people invest in them. In reality, most people allocate their money on a percentage basis in equities, bonds, cash, maybe gold for some and they reallocate those percentages as their confidence in markets changes. Some just buy balanced funds that do it for them, garnering a fairly mediocre return in a strong bull market but far more sheltered from risk on any downturn.
My guess ( unresearched ) is that most investors were under invested in equities in 2019 after being scared off to some degree by the correction in late 2018. Such is the reality of markets, people don't want to pay less on the corrections because of fear but feel they are being left behind after prices appreciate significantly. I am happy I pretty much captured the entire move in 2019 in a year where it was easy to be shaken out by news or popular sentiment among traders and the financial press. Sometimes the best moves occur when markets are the least popular.