During the pre-modern era in which wuxia fiction is set, the average life expectancy for people in China topped out in the forties. Anybody who made it into their mid or late-forties could qualify as "old" back then, and anybody who reached their sixties and seventies (let alone eighties or older) truly deserved to be congratulated on having lived an extraordinarily long life.
In wuxia fiction, many great martial artists (such as most of the original Greats and Cheung 3 Fung) lived into their nineties and even crossed the century mark. In many of these cases, their longevity is directly attributable to their cultivation of advanced martial arts.
Many non-Greats, however, also attained very old age (especially by pre-modern standards): all four of South Emperor Deun Chi Hing/1 Deng's four ministers/students were still around at the end of ROCH, and they were only a few years younger than their liege/teacher. Ying Goo was also of the same age group, and the last survivor of the Gong Nam 7 Freaks, Ohr Jen Ngok, might have been even a few years older than they. None of these people trained in elite martial arts like the Greats did, but achieved similar longevity.