> Now imagine you save $10M a year doing it

only after the move is complete and assuming it's as successful as you think it would be. What usually happens is the migration takes on a life of its own and is a multi-year if not multi-decade project. It sucks up so much money and effort that a business could be using to actually build their business vs migration to a different database. Meanwhile, the account execs of the old system know you're moving off of it so say good bye to any kind of contract discounts or special treatment during emergencies.

There's entire graveyards of failed enterprise system migrations. The most likely outcome is eventually a compromise has to be made and now you have two systems to maintain and license, the legacy one, and the new one. With the promise of eventually getting off the old one but it never happens.

I'm on a project with a client that has 24 ERPs across their enterprise around the globe from acquisitions. Half of them are ERPs that were meant to replace another one but the transition was never completed. A big part of this project is integrating all of their sales pipelines, analytics, and history into, yet another, enterprise system.