The hard part is the replication and up time, because you can serve a ton of images from a VPS for pennies on the dollar.
But even then, images are quite simple to deal with compared to big files like videos because you don't have to chunk them. So just copying them several time and putting a load balancing in front of it will get you 99% there for half of the price, dev time included.
Founder of Gumlet.com here (we serve more than 2 billion images per day).
Here are the reasons image processing on VPS is hard.
- Reliability and uptime is a huge concern. If service goes down, images can show broken
- When you build it yourself, you pay for image processing, bandwidth AND developer time. image processing at multiple terabytes and half a million image processed is not trivial ( inputs can be crazy and output needs to be modified as per the requesting platform)
- Images form a big part of Google web vitals so slow image processing can hurt LCP score.
- Newer formats like AVIF and JXL are increasingly complex. They need way more processing power than plain old JPEG.
But even then, images are quite simple to deal with compared to big files like videos because you don't have to chunk them. So just copying them several time and putting a load balancing in front of it will get you 99% there for half of the price, dev time included.
For most companies, you don't need more.