The cost is not in the servers (even though that costs money too, obviously).
90% of costs of places like Facebook are wages and various other expenses that you need too once you are running operation at a similar scale.
E.g. you do need to pay for a large team of lawyers because you are dealing with a ton of copyright takedowns, cease and desists, even lawsuits every single day.
The same with large team of moderators/content reviewers because in many countries people posting illicit content (with the definition of illicit being different by country!) may get your business blocked/shut down in that country. Including seizure of domain, any hw you may there, etc.
Add to that various regulatory compliance (e.g. the the GDPR once you are above certain size), engineers to run and maintain the systems, security team to deal with any attacks that happen 24/7, accountants, secretaries, even janitors and cleaners to keep the offices habitable.
Those are the actual costs. Not your puny server in a closet.
90% of costs of places like Facebook are wages and various other expenses that you need too once you are running operation at a similar scale.
E.g. you do need to pay for a large team of lawyers because you are dealing with a ton of copyright takedowns, cease and desists, even lawsuits every single day.
The same with large team of moderators/content reviewers because in many countries people posting illicit content (with the definition of illicit being different by country!) may get your business blocked/shut down in that country. Including seizure of domain, any hw you may there, etc.
Add to that various regulatory compliance (e.g. the the GDPR once you are above certain size), engineers to run and maintain the systems, security team to deal with any attacks that happen 24/7, accountants, secretaries, even janitors and cleaners to keep the offices habitable.
Those are the actual costs. Not your puny server in a closet.