"This is not just my opinion. I can prove it to you empirically. See, as I was preparing to write my book "Get Rich Carefully," I went over the previous five years of trades made by my charitable trust. And as I reviewed those trades I noticed that far too often, my good judgment would be overcome by excessive skepticism."
That is, there were times when Cramer identified companies with solid balance sheets, good future potential and excellent management teams, yet he let skepticism prevail instead of trusting the research and his instincts.
Case in point: Walgreen.
In 2012, Cramer found himself intrigued by Walgreen's prospects, and after doing boatloads of research, he concluded around $40 the stock was a "buy."
"I thought it was a terrific value play with excellent management under the leadership of CEO Greg Wasson, especially after the company bought Duane Reade, the big New York City based drugstore chain, and beautifully refurbished those stores."
However, Walgreen became embroiled in a high profile dispute with Express Scripts and stopped filling prescriptions for those consumers. In turn, shares of Walgreen tumbled. Then, a short while later, Wasson dropped $6.7 billion for a controlling stake in Alliance Boots, a health and beauty retailer based in Europe.
"For me, that was the last straw," Cramer said.
Even though Wasson explained his strategy to Cramer personally, and even though Cramer still admired Wasson's abilities, he let broad skepticism color his thinking and he turned negative on the stock at $29.