How would you design a news feed system for a social media platform to handle both regular users and celebrities efficiently?

Imagine you have a big box of toys, and you want to show them to your friends. If you give each friend a toy when you get it, that's like 'fanout on write'. But if you wait until they visit and then show them all the toys, that's like 'fanout on read'. Each way has its own challenges and benefits.