Serverless isn't "cheap". It's rightsized. If you aren't serving 24/7, it makes sense to move to an on-demand model. However if you compare the unit of compute

Serverless isn't "cheap". It's rightsized. If you aren't serving 24/7, it makes sense to move to an on-demand model. However if you compare the unit of compute pricing, Lambda is comparable to other services, and likely more expensive than buying compute wholesale. You can just buy it in smaller portions.