Table baseline: Musk was born on 28 June 1971, so he is 55. On the SSA 2023 period life table, 999 of the 88,436 US men alive at exact age 55 reach 100, about 1.1%. Wealth and non-smoking move that up (the richest 1% of US men live about 15 years longer at age 40 than the poorest 1%, Chetty et al., JAMA 2016), which for a 55-year-old roughly triples the century odds to the low single digits, still well short of this market's 19%. The remainder is a bet on medicine arriving in time, and its clock is knowable: the first placebo-controlled lifespan trials of anti-aging drugs are in dogs (TRIAD, Loyal's STAY study), reading out around 2029 to 2031, and a human lifespan trial started after a positive dog result takes about 21 years from enrolment at 65, so human lifespan evidence lands in the 2050s, when he would be in his 80s. The arithmetic with sources (mine): https://w0lph.github.io/k9/why-dogs.html?v=2

Why the path to human longevity runs through dogs

Computed from the cited life tables and trials: a lifespan answer takes 4.6 years in dogs and 21 in people; dogs share our environment and diseases, lifespan has already been extended in dogs, and a regulator has accepted lifespan extension as an indication for dog drugs.