Yes, good catch! Add in maybe 20% for management and it's still a manageable amount of headcount. The $1M/advertiser does a lot of the lifting here - so I looked into it a little more. In 2016, Twitter had 130k advertisers[0], some can self-serve but many need inside sales reps.

Fermi estimates are crude, but the point is there are many non-engineering functions that are absolutely critical. Many HN folks seem to think like Elon, that these roles are unnecessary. I disagree.

[0] https://www.marketingdive.com/news/twitter-increases-number-...