Earlier quoted context omitted.
I never followed this chain of logic. The whole point behind the stock market is to treat any commonly traded stock as a liquid asset. Why do you think that this fails with respect to Bezos and Gates?
Bill Gates started selling off his microsoft stake in the late 90s. It took him more than two decades to get from 49% ownership down to the 1.9% he has today. It's hard for figure heads to divest without crashing the stock because it carries substantial signal risk. The stock market is only liquid at smaller scales, bigger transactions will have dramatic effects on the price.
You are right that insiders selling can be a signal. That's why we have laws that govern their actions. But that's because it is assumed Gates knows more than the average MSFT investor.
Yes, if Bezos woke up tomorrow and wanted to crash AMZN by selling his shares, he could. But he routinely liquidates over a billion dollars worth a quarter.