CDC mortality tables [1] are kind of eye opening for those who don't realize how brief life is. Average age range on HN is probably in the 25-44 year old bracket. That bracket has an approximate mortality rate of 140/100k per year. HN has what, 5 million or so monthly users? So that means of all of 'us', it's expected that around 7,000 HN readers age 25-44, die each year. That's fairly close to 1 death per hour.
[1] - https://www.cdc.gov/nchs/data/dvs/MortFinal2007_Worktable23r...
Your CDC figure is an average over all genders. Assuming hacker news readers are disproportionately men, the mortality rate is even higher, since men die younger than women on average.
>it's expected that around 7,000 HN readers age 25-44, die each year
That's not true unless HN readers are a representative sample of the overall 25-44 population, which they aren't. Higher-income/SES is associated with a lower mortality rate than the overall population average.