The No. 1 ‘hidden’ skill behind billionaire Bill Gates’ success—it works ‘in any field,’ says psychology expert

Optimism and pessimism are hard to deal with.

Pessimism is vital for survival, and it helps us prepare for risks before they arrive. But optimism is equally essential. The belief that things can — and will be — better even when the evidence is murky is one of the most essential parts of everything from a sound relationship to making a long-term investment.

Optimism and pessimism seem like conflicting mindsets, so it’s more common for people to prefer one or the other.

But in my book, “Same as Ever: A Guide to What Never Changes,” I write about why knowing how to balance the two has always been — and always will be — one of life’s most important skills.

Bill Gates is a great example of how effective this hidden skill is. From the day he started Microsoft, he insisted on always having enough cash in the bank to keep the company alive for 12 months with no revenue coming in.

In 1995, he was asked by Charlie Rose why he kept so much cash on hand. Things change so fast in technology that the next year’s business wasn’t guaranteed, he said — “including Microsoft’s.”

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In 2007, he reflected: “I was always worried because people who worked for me were older than me and had kids, and I always thought, ‘What if we don’t get paid? Will I be able to meet the payroll?’”

Here, optimism and confidence is mixed with heavy pessimism. What Gates seems to get is that you can only be an optimist in the long run if you’re pessimistic enough to survive the short run.

An important thing to recognize here is that optimism and pessimism exist on a spectrum.

At one end, you have the pure optimists. They think everything is great, will always be great, and see all negativity as a character flaw. Part is rooted in the ego: they’re so confident in themselves they can’t fathom…