Robert Kraft is very wealthy, but what's stopping you from reaching that same level of success? As summarized in our five fundamental rules to wealth building, becoming wealthy in a modern capitalist economy is not complicated. There's actually only three variables:

1. Your starting capital
2. Your earnings after expenses
3. The compound annual growth rate (CAGR) of your savings

Most people start with zero or very little, so if you weren't born into wealth, don't fret! The majority of the fortunate folks listed in our Grizzly Bulls’ Billionaires Index came from middle class or lower backgrounds. The most distinguishing characteristic of the group is their ability to consistently earn a high CAGR on their savings.

Every billionaire has a unique strategy to achieve high CAGR. For Robert Kraft, Manufacturing and New England Patriots are the primary sources. Whether you choose to invest your savings in your own businesses or the businesses of others is not as important. The salient piece of the puzzle is ensuring that your hard-earned savings are generating sufficient CAGR to reach your long term goals.

Most people simply invest their money in index funds and call it a day. There's nothing wrong with this approach, but it guarantees relative mediocrity. To achieve greatness, you need to invest your money to earn higher than average returns. In the long run, better investors will always finish ahead of better earners.