There once was a time that building your own CDN would have been unthinkable - complicated, expensive and not worth the hassle, considering that there were a number of well-known commercial CDN providers available who could make it easy to distribute content reliably across the geographies a company wanted to reach. CDN vendors offer the full package: hardware, software, network and so on, meaning that, for a long time, for most companies, convenience trumped other considerations.
Lately the content delivery industry looks more like a meteorological website for alpinists than anything else.
We, as users, are consuming (and producing) more content than ever, Cisco predicts that “global Internet traffic in 2021 will be equivalent to 127 times the volume of the entire global Internet in 2005. Globally, Internet traffic will reach 30 GB per capita by 2021, up from 10 GB per capita in 2016.”