Group 1 - The article discusses the longevity of American billionaires, noting that one-fifth are over the age of 80 or 90, and highlights that this does not necessarily lead to retirement [2][8] - Warren Buffett, at 95, continues to actively participate in his company, Berkshire Hathaway, and has announced plans to step down as CEO by the end of the year, although he will remain involved in some capacity [3][20] - The article mentions that there are currently a record 36 billionaires aged over 90 in the U.S., with 150 more aged over 80, contrasting with the general population's life expectancy [8][9] Group 2 - The article provides examples of other billionaires over 90 who remain active in their businesses, such as George Joseph, who is 103 and still serves as chairman of Mercury General [4][11] - Rupert Murdoch, at 94, retains significant influence in his company despite stepping down from the CEO role, and his succession plans have faced legal challenges [5][9] - The article notes that the high percentage of billionaires living past 80 may be attributed to their access to superior healthcare, nutrition, and lifestyle choices [9][10] Group 3 - The article lists the ten oldest billionaires in the U.S., including George Joseph (103), Alice Schwartz (99), and Warren Buffett (95), detailing their contributions and current roles in their respective companies [11][12][20] - It highlights that many of these billionaires attribute their longevity to active engagement in work and maintaining mental sharpness through problem-solving and physical activity [10][11]