when do you really need a cdn

hey everyone, been thinking about our caching strategies lately. weve got some internal caching solutions that are working okay for our core users, but were seeing a lot of latency for our global audience. im starting to wonder when a Content Delivery Network (CDN) becomes a non-negotiable part of the infrastructure. what are your experiences? at what point did you decide to add a CDN, and what were the biggest wins or challenges?