Here's a recent article by Larry Swedroe that highlights why entrepreneurs and other successful businesspeople frequently make bad investors.

The very success of the active investors creates a behavioral problem. Because of their successes, they’re not only confident of their skills, but they’re also confident in their ability to tolerate, manage and control risks. These behavioral traits can lead to them to the mistake of failing to consider that the strategy to get rich — work hard and take big risks, typically by owning a business — is entirely different than the strategy to stay rich — minimize risks, diversify the risks one takes and don’t spend too much. The former is about wealthaccumulation, the latter about wealth preservation. Those who have already achieved sufficient wealth to support a quality lifestyle can either focus on the preservation of capital by having a low allocation to risky assets like equities, or they can try to accumulate even more wealth by having a large allocation to risky assets.

Read the whole article, How you earned your money plays a big role in your investing mindset.