AWS is one tool but its a lot like the proprietary computing ecosystems that have existed for a long time (remember the Micro$oft days?). It offers convenience

AWS is one tool but its a lot like the proprietary computing ecosystems that have existed for a long time (remember the Micro$oft days?). It offers convenience in return for lock in and very high margins. Theres no clear answer but its definitely not a clear cut decision where AWS is guaranteed to save money. There are 2 major costs that are overlooked by the in-house crowd, which are operational maintenance cost (an increasingly rare and expensive skillset), and also the cost of downtime -- how much does it cost you when your team of data scientists are blocked because of a failed OS update etc. That being said, hiring competent people to maintain AWS properly isn't cheap either -- and it is quite easy to start running up very wasteful AWS bills on things you don't need. As always there's a tradeoff -- the key is to choose a path and to execute it well.