During the dot-com era, there was an even more serious form of a psychological problem called "financial idiocy." I heard it manifested a few times in callers to a financial talk-radio show who insisted to the host that from that day forward a company's earnings would no longer be a factor in its stock price.
"You heard it right there, folks," the host said (and you could almost see him shaking his head), "and you wonder why I am advising all of my listeners to cash out of this dot-com nonsense right now?"
I was telling everyone I knew to sell their tech stocks in August of 2000. That's when I got out, when the writing on the wall became ever so apparent.