So when he was asked what he would do if he lost everything, here's what he said he would do first:
"I would get a job as a bartender at night and a sales job during the day, and I would start working. Could I become a multimillionaire again? I have no doubt."
Why does he feel that way? Success is based -- in almost any field -- on solid sales skills.
INC. TODAY'S MUST READS: McDonald's Just Did Something Brilliant to Its Drink Trays That Can Never Be Undone
Don't believe me? Granted, many people feel "selling" implies pressuring, manipulating, misleading--the sell-at-all-costs salesperson stereotype.
But if you think of selling as explaining the logic and benefits of an idea, a decision, a project -- of anything worthwhile -- then everyone needs sales skills. Everyone needs to have the ability to convince other people that an idea makes sense, to show bosses or investors how a project or business will generate a return, or to help employees understand the benefits of a new process.
Sales skills are, in essence, communication skills. And since communication skills are critical in any business or career, the best way to learn how to communicate well is to work in sales -- because great salespeople are great communicators.
Gain sales skills and you'll be better at everything: bringing investors on board, lining up distribution deals, landing customers, motivating employees. Especially in the early stages of starting a company, seemingly everything you do involves some form of sales.
That's why spending time in a direct sales role is an investment that pays off for the rest of your life.
For example, when you learn to sell:
1. You learn persistence.
Salespeople hear the word no all the time. Over time, you'll start to see a no as a challenge, not a rejection. And you'll figure out what to do next.
2. You build self-discipline.
When you work for a big company, you can sometimes sleepwalk your way through a day and still get paid. When you work on commission, your credo is, "If it is to be, it's up to me." Working in sales is a great way to permanently connect the mental dots between performance and reward.
3. You gain confidence.
Working in sales is the perfect cure for shyness. You'll learn to step forward with confidence, especially under duress or in a crisis.
4. You learn to negotiate.
INC. TODAY'S MUST READS: 20 Years Ago, Steve Jobs Demonstrated the Perfect Way to Respond to an Insult
Every job involves negotiating: with customers, with vendors and suppliers, even with employees. Salespeople learn to listen, evaluate variables, identify key drivers, overcome objections, and find ways to reach agreement--without burning bridges.
5. You learn to close.
Closing a sale is part art, part science. Getting others to agree with you and follow your direction is also part art and part science.
Many people find it hard to ask for what they want. If you want to lead people, you must be able to explain what you want -- and then close. That's why great bosses know how to close.
Still not convinced? Think of it this way: The more intimidating or scary a position in sales sounds, the more you need to take one. You'll gain confidence and self-assurance, and the skills you gain will serve you well for the rest of your business -- and personal -- life.
So if you're an aspiring entrepreneur, set aside your business plan and work in sales for a year or two. If you're a struggling entrepreneur, take a part-time sales job. One reason you're struggling might be that you need to improve your sales skills.
"Knowing what my sales skills are and the products that I am able to sell," Cuban says, "I think I could find a job selling a product that had enough commissions or rewards for me."
And that would generate enough seed money to let him start his own business and let him use his sales skills to make money for himself, not for an employer.
Successful business owners -- successful people in general -- spend the majority of their time "selling."
INC. TODAY'S MUST READS: Google Spent 2 Years Studying 180 Teams. The Most Successful Ones Shared These 5 Traits
Learn how to sell.
It's the best investment you will ever make.
Mark Cuban says so.
RELATED: Best Mark Cuban business quotes
More on Inc.com:
Every Great Boss Says These 4 Simple Words, Each and Every Day
Want to Accomplish More in Less Time? 9 Things the Most Effective People Always Do
The Best Way to Deliver Bad News to Employees, Teammates, and Customers