Do you also have a source showing that the number of engineers required scales linearly with number of users?

It in fact scales exponentially.

Internal sources only, but topics like regionalization, localization, bespoke caching implementations, hardware-level optimizations, content moderation, policy adherence (e.g. GDPR, CCPA), long-term monetization (especially if supporting advertisers as a direct customer), 3P support, public APIs, documentation, SRE (a fledgling product doesn't need 5 9s), analytics (internal and for advertisers and 3P partners) and for the most part, security, are non-exhaustive examples of things you can mostly ignore when your product supports 10M users that are unavoidable when your product supports half of the US, a good chunk of the rest of the world, and other large businesses that consume you at large business scale.

You listed a bunch of requirements without an argument that fulfilling those requirements actually entails an exponential growth in employees.

> Well, let’s see. IG was acquired by FB in April 2012 and had somewhere above 10M users at the time. Around the same time, Twitter had around 140M accounts in US alone, nearly 500M worldwide.

So increasing your user base by one order of magnitude requires increasing the number of employees by more than two orders of magnitude? Rate of employee acquisition should probably never outpace rate of user acquisition, so I think that's a pretty clear sign that something was off.

Was instagram selling advertising to giant brands yet when they were bought? Sales staff balloon because they are really good at selling themselves to hiring staff and also because any brand that pulls in more than $10M in revenue expects to be treated like the only king of the world in pretty much every interaction and literally requires handlers, and the number of handlers required scales with the size of the brand.

You can potentially solve the handlers issue by being ruthlessly cutthroat. If they want hand-holding, they can hire a third party to manage advertising on Twitter. They probably already do in fact, so if you are a third-party, do your job and know your tools.

As for sales staff being good at selling themselves, agreed, so maybe Musk's ruthless firing spree will end up as a good thing. Maybe.

>You can potentially solve the handlers issue by being ruthlessly cutthroat

No, that just results in those businesses and brands leaving you, unless you can provide them a LARGE revenue stream that is impossible to get anywhere. A large brand will absolutely give up a little money just to spite you and your company for not treating them like god.

That's true, but also hardware and software hasn't stood still in the past decade.

I'd definitely like to hear more about the scale differences. So far at best, you've accounted for one order of magnitude. How do you explain the second?