Disagree on many points, stocks are used as collateral for debt financing, their prices can definitely trigger cascade effects and losses even if not actually sold.

Overreaching arguments that sellers are like selling because they plan to buy when it's lower, no proof and a limited view, in fact in my also overreached argument I would say the opposite, most people just want to put money on an ETF and hold it until retirement, without having to touch it, they sell because something is forcing their hand and they need the liquidity to pay for something else.

Gold is definitely a hedge for inflation and market instability which is why it's had such a big run up these past few months, and they are definitely used in most diversified portfolios, yale fund as an example, (I don't know where you got this notion from)