Look, the issue is this for a small business: you have 5 engineers, do you spend $150 a month to pay AWS to look after hosting your stuff? or do you pay an engineer >>$150 a month to create, manage and maintain a bespoke infrastructure?

Sure, you might be lucky with the engineers you have, they might be savvy enough to wrangle a couple of hosts for you. But are they backed up? what's the disaster recovery procedure like? How do you rotate keys/passcodes, how do you audit who has access?

Unless you are doing something wrong, your biggest costs are engineering time.

> disadvantage of strongly coupling your infrastructure and often your code to AWS.

you can say the same thing about any infrastructure. yes, you can migrate k8s from one physical host to another. But, for that to be effective, you need to not be using any manage services. So that means you're on the hook for all the painful things like DB state and recovery, messaging systems, etc,etc,etc.

Then you think as a business, what are you actually spending money to do? maintain the code that makes you money, or maintain the system underneath it, just in case you might need to move to save opex thats almost certainly going to be less than one engineer.

98% of companies have no issue with scale. They have issues with availability, features, backups, speed. exchanged 10% of an engineer's salary to never really have to deal with any of those issues is a good deal for most[1] companies

[1] most, but not all. However unless you are getting close to spending 1 engineer in AWS fees, moving to self hosting is nothing but premature optimisation.