Self-made millionaire: Millennials are falling behind boomers—here's how they can catch up

In 2017 millennials are making a full 20% less than their boomer parents were making at the same stage of life. Millennials have a median income around $40,000 a year .

The college education that boomers pushed their children to get, thinking it would secure their wealth, isn't enough. The wealth hasn't materialized. Millennials are more educated than any other generation in history — and they have half the net worth their parents had. We aren't living in mid-twentieth-century America anymore, no matter what Donald Trump promises to return us to.

Nearly half of all millennials are living in their parents' basements. Many others are rooming with two or three other millennials in a small apartment, trying to pay down their $40,000 student debt from their $40,000 salary.

Here's the truth of the matter: Anyone making $50,000 or less a year will suffer for the rest their life unless if they do something to change their situation.

If you're going to stay at $50,000 or less , you're never going to be able to take a decent vacation. Before you go on vacation you'll worry about money; while you're on vacation you'll worry about money, and when you get back you'll worry about money. It's not a real vacation when you're so anxious about what you're spending.

A vacation is when you don't worry about what you're spending before you get there, not worried about what you spend when you get there, and definitely not worried about what you spent when you get home. A vacation is not staying at the Holiday Inn so you can get a free bagel for breakfast. When you are a millennial making 40K a year, is a vacation even an option?

Millennials need to pay the price today so they can pay any price tomorrow.

And yet they're not taught that. There's not one course on how to get rich at school.

The collegiate and high school system in America is ridiculous. I know because I've been through it. Professors could teach me 17th century British Literature but nobody would tell me to go and make more than $50,000 a year, not to mention how to get rich.

The problem for millennials is that most have never been taught the importance of sales. Everything in life is a sale, and if you can learn to sell, there is no limit to what you can earn.

People make money from two things: Knowledge or the ability to get money. Doctors and lawyers have knowledge and get paid for it. If you don't have special knowledge, then you better know how to go and get money from the marketplace by selling things.

If you know sales, you can go out and sell your own product or someone else's . The more you can sell the more you should earn. Get a job that pays commission and you can be in control of how much you earn. Even if you are an hourly worker, if you can sell more you will become more valuable to your company and have a better chance of promotion.

Mark Cuban agrees: No matter what company you work for and no matter what industry, learning sales is key to becoming rich . The answer for any millennial out there tired of being financially strapped is to raise their skills.

When I was 25, I was broke too. It wasn't until I committed to learning sales that I began to climb out of the middle-class and achieve financial freedom.

Millennials must create wealth for themselves. Going to college and buying a home is not going to work. Any millennial dissatisfied with $40,000 a year must learn the art of sales. The only other option is falling even further behind boomers.

Grant Cardone is an entrepreneur, New York Times best-selling author, and sales training expert.