Social media? So last year. Youth? Overrated. The new Forbes list of the richest Americans shows that old money endures, and that the would-be kings of the second dotcom age have been served.

The top three American billionaires in this year's Forbes poll have a combined age of 206. Bill Gates, 56, heads the poll again with a fortune of $66bn, $7bn more than last year. This is his 19th year in a row at the top. Warren Buffett, 82 and the last man to oust his friend Gates, comes in second at $46bn and Oracle's Larry Ellison, 68, is third at $41bn.

Conspicuous by their absence in the top ranks are the new tech titans, most notably Mark Zuckerberg of Facebook. The social media media moguls lost a combined $11bn in one year, according to Forbes. The biggest loser was Zuckerberg, whose net worth has dropped $8.1bn, more than anyone in the list this year, and which prompted a fall from 14th place to 36th.

Not that Zuckerberg is poor. The 28-year-old is now worth $9.4bn, the same as News Corp chairman Rupert Murdoch, 81. Nor is Zuckerberg alone among his social media peers in losing cash this year. Mark Pincus, the founder of Zynga – the gaming firm behind Words With Friends and Draw Something – has also been burnt, as investors found the games to be less addictive than they first thought. Zynga's shares have fallen more than 66% since their debut last December. Pincus made his debut in the list last year and is out this year.

But the social media backlash didn't dent the fortunes of America's wealthiest. The average net worth of a Forbes 400 member is $4.2bn this year, up from $3.8bn in 2011. The total combined net worth of the 400 Club was $1.7tn, up from $1.5tn in 2011. Canada's gross domestic product (GDP) was an estimated $1.7tn in 2011.

Net worth increased for 241 members, and decreased for 66 members. There were just 45 women in the list, up from 42 last year. The wealthiest was Alice Walton, one of the heirs to the Walmart fortune and whose $26.3bn made her the eighth richest person overall.

The Waltons occupy four of the top 10 slots, but are not the only example of family fortunes at the top of the list. Charles and David Koch, industrialist billionaires and favourite funders of all things rightwing, came in joint fourth, with a combined fortune of $62bn.

The youngest man on the list, Facebook's Dustin Moskovitz, 28, and the oldest, David Rockefeller Sr, 97, shared 151st position with fortunes of $2.7bn. Also in at 151 was Oprah Winfrey.

Forbes 400. Photograph: Michael Prince/AP

Forbes managed to cajole $126bn worth of billionaire to pose for its latest cover celebrating their philanthropy. Gates, Buffett, Winfrey are all there. And Jon Bon Jovi. He's not on the list, but a video explains – sort of – that he's there because he gives a lot to charity.