Both ends of that spectrum are largely insufferable.
Should you use RDS, or run your own databases on top of AWS? They're super opinionated about this despite the fact that they print money either way.
It's the opportunity cost of you building that thing instead of building something that's more aligned with your core business.
This particular point is brought to you eight years ago by @Splunk.
People will weigh in on this as soon as I hit "Tweet," but the honest answer is "it depends."
And your TCO analyses are a nest of lies.
As I said, I'm somewhere in the middle on this.
That's easy stuff. The nuanced stuff... carries more weight. :-)
You're not going to sit down and beat together a better database over the weekend than a database vendor is going to be able to deliver (once you remove MongoDB from the list).
Same story with logs, monitoring, and a pile of others.