A previous employer of mine had paid 96k a year to use a client software on a per database installation basis (12k per license, 8 database installations across the company worldwide, for a total cost of 96k/year)..

However this software was a trivial CRUD app we used for dealing with CAD files. To be clear: we completely owned and managed the back end database ourselves, and just used the app as a client interface for searching/creating CAD files (which was super slow btw).

I could've created an equivalently functional client app within a week or two, that was both faster and more scalable. Doing so would have saved the company an obvious 96k a year in recurring costs, along with increased productivity. It might have taken a while longer than a week to deploy to users, but nonetheless would have alone justified my yearly salary. Additionally it wouldn't have taken 100% of my time a year to support or maintain such a client.

However, I couldn't convince managers it was worth it to rewrite it in house, despite no new features being added to the software by the vendor for over 8 years! Frankly, I'm still not sure why that was (ignorance I'd say), but I think it said how much I was respected there... so I left.

Actually, I lied - I still work there and am in the process of finding a new job. Frankly, it's stuff like this that makes me think I should just get with the times and start my own niche SaaS company and do "Rent-Seeking" to ignorant companies such as this, since they don't understand when something is cheaper to be done in house...