Depends. Some CDN are more than worth it. Hetzner has weak DDoS protection for example. Some CDN have caches inside the ISP network. It doesn't even get out. There are also cases where the local ISP may not peer with you even if you are in the same region. OVH was famous for this in Asia. It's not enough to be in the same region.
Different perspectives from different requirements. In my case I have to serve API requests that can't be proxied. Most of the data is API, it's bigger than the statics.
Using a CDN for static assets for North America just doesn't seem worth it to me.