Whatever the exact number may be 7000 is going to be a pretty reasonable ballpark, and it's certainly orders of magnitude higher than most people would expect.
7K/year is for the healthy, affluent, tech-worker-heavy population already. For the general population, US, is ~ 12K/year.
Not that higher-income/SES is necessarily representative in a supposed 5m strong HN readership - it would be all kinds, from all around the world. SV startup / FAANG types are just a small slice.