- maintaining the number of clients alone is a gargantuan task. Almost every TV manufacturer has a different OS, and many TV models have different OS, plus all of the different consoles, phones, etc - The pure engineering of pushing that many bytes around the world 24/7. - Then storing information about those users for advertisers. https://netflixtechblog.com/revisiting-1-million-writes-per-... - Security, because if they are found negligent (ie making it easy for people to make illegal copies), there goes their business. - Constant product tweaks on the above thousands of clients to make the UI experience consistent across clients. - Performance improvements to keep users engaged. - AI that surfaces what customers want. - Data storage to deal with all of the content they have. - Dynamic content serving based on where in the world you are. - etc.