The consequence of running a database poorly is lost data.
At the end of the day they're all just processes on a machine somewhere, none of it is particularly difficult, but storing, protecting, and traversing state is pretty much _the_ job and I can't really see how you'd think ingress and DNS would be more work than the datastores done right.
Now with AWS, I have a SaaS that makes 6 figures and the AWS bill is <$1000 a month. I'm entirely capable of doing this on-prem, but the vast majority of the bill is s3 state, so what we're actually talking about is me being on-call for an object store and a database, and the potential consequences of doing so.
With all that said, there's definitely a price point and staffing point where I will consider doing that, and I'm pretty down for the whole on-prem movement generally.