when do you really need a cdn tho, like whats the tipping point

ive been thinking a lot about performance lately, especially how to serve static assets quickly to users all over the world. Weve seen a lot of discussions about caching here, but im curious about when a Content Delivery Network (CDN) specifically becomes a must-have versus just a nice-to-have. Is it purely based on user geography, traffic volume, or are there other factors like asset size or type that push you to adopt one? Whats your experience with CDNs? When did you decide it was time to pull the trigger?