If you pull an application apart and squeeze it into managed services, your costs can drop by an order of magnitude depending on your availability requirements, engineering related costs, etc. A good article written by Spotinst's CEO [1]

Not trying to shill, not everything should be serverless, and I should work to be more platform agnostic, but AWS has been great to and for me, AWS marketing material [2]

[1] https://medium.com/@amiram_26122/the-hidden-costs-of-serverl...

[2] https://aws.amazon.com/serverless/