It's never a bad time to be a billionaire, but this is an especially good time to have a 10-figure bank statement.

The 10 richest people in the world added $402 billion to their already enormous fortunes in 2021.

The biggest gainer was Elon Musk, who started the year with a net worth of $156 billion and will end it with around $277 billion, according to the Bloomberg Billionaires Index. The Tesla founder said he's planning to pay more than $11 billion in taxes.

Musk's 121-billion-dollar gain was smaller than the $140 billion he made in 2020, but was more than enough to make him the richest person alive by a long shot.

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He has been spending part of that fortune on his rocket hobby. SpaceX, the private rocket company he founded in 2002, has already launched more than 1,600 satellites, including a recent launch on December 18.

His closest competitor and fellow rocket-building billionaire Jeff Bezos will enter 2022 worth $190 billion. That's a mere 4.5-billion-dollar gain since this time last year.

The 57-year-old, who stepped down from his CEO role at Amazon in July, now spends most of his free time vacationing with girlfriend Lauren Sanchez. The PDA-heavy couple was spotted on a yacht in St. Barts over Christmas.

In keeping up with the billionaires, Facebook founder Mark Zuckerberg added nearly $25 billion to his fortune in 2020. He's worth $128 billion, according to Bloomberg.

Zuckerberg, who changed the name of Facebook's holding company to Meta this year, has had a turbulent year, which saw whistleblower Frances Haugen accusing him of putting "profits before people," and him later raising the ire of Hawaiians after he added 110 acres to his controversial 1,500-acre estate in Kauai.

Microsoft founder Bill Gates began the new year worth $139 billion. He entered 2021 with a value of $132 billion. His former wife, Melinda French Gates — who ended her 27-year marriage to Bill in August — reportedly has a net worth of $11.4 billion herself.

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Google co-founder Larry Page cracked the 12-digit club in 2021 by adding $47 billion to the $83 billion he had coming into this year. Fellow Google co-founder Sergey Brin also enjoyed that distinction by becoming worth $125 billion, thanks to a 2021 gain of $45 billion.

While it was a good year for US businessmen, French luxury goods peddler Bernard Arnault also saw his fortune leap to $176 billion after hauling in more than $61 billion. He's the only billionaire outside the US to have cracked Bloomberg's 2021 top 10 list in terms of total wealth.

All 10 of those male power players are worth more than $100 billion. The 11th-wealthiest person on the list, also from France, is Francoise Bettencourt Meyers, who's valued at nearly $94 billion. The heiress is the richest woman alive.