Buffett is the No. 2 wealthiest American (behind Bill Gates of Microsoft), according to Forbes magazine. Buffett's worth: $52 billion.
Managing director, tax and accounting expert at Lehman Bros.
Biggest mistake:Waiting too long to sell.
"The investment (my wife and I) made in a company called USA Classic seemed, at the time, a can't-miss proposition," Willens says, "but turned out be the worst investment we ever made.
"The apparel they were offering seemed very attractive. Their style seemed to be unique. We were comforted by the fact that they had a company that owned a substantial amount of their stock … that would be in the position to support it and weather any storms that might arise. We also were impressed with their management."
After the company's initial public offering in the early '90s, "It ran into some operational problems," Willens says. "The products were not always in the store in time for the season. (Management) kept saying that these problems were being resolved. We felt they would get these problems straightened out, so we continued to buy the stock on the way down on the theory that … if the average cost was so low, we'd have a profit on all of our stock in the aggregate" once the price recovered.
"The company pretty much ran out of capital before the operational problems could be rectified," says Willens, who lost about $140,000 on this investment. USA Classic filed for bankruptcy protection in 1994, two years after its IPO.
What he would have done differently:
If we had to do it over again, "There's no doubt that I would have a stop order in mind, whether it's a formal stop-loss" or guidelines in my mind of when to sell, Willens says. "I would never average down with a small company like this again. The fact that you may have identified what might be, under better circumstances, a great company is nothing" if it doesn't have a cushion of capital to weather downturns.
"We've never forgotten this experience," he adds. "It's made us more conservative (investors). In a way, I'm glad it happened because it changed our thinking about investing."
CEO of the national real estate brokerage of Coldwell Banker
Biggest mistake:Began saving too late.
After Gillespie earned a graduate degree in recreation and park administration in 1968, he says, "Like most people in their 20s, I had a good time." He worked as a grade-school teacher and coached sports, and then worked with youth programming at two YMCAs before becoming an executive director at a YMCA branch.
"When I was 22, I was not thinking that I'd ever be 62 and looking at retirement," says Gillespie, 62. By the time he started his career in real estate at age 30, he had nothing saved.
"I lost eight years of investing," he laments.
Of course, he's since made up for lost time. For several years, he and his wife, Jenny, bought a rental house each year. They now own nine rental houses, two apartment buildings and a small office building. "The rents on the properties are like dividends on stocks," Gillespie says, "and we've seen what appreciation has done."