Money. It isn't everything, but it's sure better than nothing.

There are more billionaires alive on the planet now than ever before. It's not just because there are more people or because, due to inflation, $1 billion today is worth less than $1 billion 20 years ago. Instead, it's because of opportunity, change--and consolidation.

Now, a new study says that there are some commonalities--some obvious, some not so much--in the ways modern billionaires accumulate their wealth.

Of course I'm not suggesting that if you follow their strategies you'll become wealthy and successful yourself. (If that's what you're interested in, maybe check out the complimentary bonus e-book I put together: The Big Free Book of Success, which you can download here for free.)

That said, there's nothing like observing how the wealthiest people out there got their money and taking a little mentorship and inspiration from it. Here are the five key things they have in common, according to a recent analysis by CityLab's Richard Florida.

1. They're self-made, at least those of them in the U.S.A.

This is good news, I think. While European billionaires are more likely thank not to have inherited their wealth from mommy and daddy,  Americans are far more likely to have created their fortunes themselves. 

Moreover, it's old money over there: "20 percent of Europe's inherited fortunes were four or more generations old, compared to less than ten percent in the U.S.," according to data from the Peterson Institute for International Economics (link opens .pdf).

2. They got started young (and made their money early).

Rattle off the names, and it will make sense: Bezos, Zuckerberg, Brin, Page, Gates, Buffett. They all got started early, and they crossed the $1 billion threshold before an age when most of us are still trying to figure out what we want our careers to be.

Interestingly, this holds true only in the United States. In Europe, billionaires and their businesses are older--reflecting the fact that in the last 20 years or so, recession or not, America has been the real land of economic opportunity.

3. They go where the money is.

Often, that means that they either go overseas or are from there. China, especially, but also other emerging economies around the world.

"Billionaire wealth in emerging economies increased from less than $500 billion in 1996 to roughly $2 trillion by 2015, compared to around $3 trillion for advanced nations in 2015," Florida writes.

4. They focused on technology....

Again, when we think of the household names who have accumulated $1 billion or more in the U.S., the tech companies spring to mind: founders of companies from Alphabet to Uber. 

Again though, Florida points out, this is primarily an American phenomenon: "The U.S. has a much greater number of self-made tech billionaires (56 billionaires, or 12 percent) compared to 17 billionaires, or just 5 percent, in Europe."

5. ...Unless they made their money in finance.

Figures, right? The only category minting more fresh billionaires than technology? You guessed it.

"More than 40 percent of the growth in the U.S. billionaire population can be attributed to finance--particularly hedge funds," Florida writes, "compared to 14 percent of the growth in Europe and 12 percent in other advanced countries."