Out of the market before the crash

[snopes]

Comment: I have frequently heard a story about a stock broker who got out
of the market just before the 87 crash because of a tip given him by a
layman. He reasoned that if so many non-brokers were in the market, it
was unstable and therefore time to get out.

I have heard the tip attributed to a taxi driver and a shoe-shiner. Have
you ever heard this tale, and does it have any basis in fact?