For some use cases the cost saving is a big deal e.g. resizing an incoming stream of images.
But for the majority of apps it doesn't save that much. And it still pales in comparison to the cost of the engineers. Which often spend significantly more time to build, debug, test etc a serverless app than one they just throw on an EC2 server.
“Apps” is a pretty vague description of an application, but if you’re writing a server it’s just as easy to “just throw” the app on lambda as it is on EC2.
In general I ask myself if my new server can run on a lambda and if it can’t then I reach for something else. Most of the time it can.
But for the majority of apps it doesn't save that much. And it still pales in comparison to the cost of the engineers. Which often spend significantly more time to build, debug, test etc a serverless app than one they just throw on an EC2 server.