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.

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.

But the profitability requieres a big tech team regarding ads and recomendation algos etc.

And moderation requieres humans but also a big tech team regarding bots, known offenders, etc.

it's not exclusively a tech problem but in a tech company tons of those responsabilities will be handled, addressed and solved by product and tech teams. And on 10 people, no matter how smart, they got no chance

Nobody knows what the secret hashtags are. The claim is unverified and unverifiable, and probably signal-boosted from a single wild tweet.