Working in a university Lab self-hosting is the default for almost anything. While I would agree that cost are quite low, I sometimes would be really happy to throw money at problems to make them go away. Without having the chance and thus being no expert, I really see the opportunity of scaling (up and down) quickly in the cloud. We ran a postgres database of a few 100 GB with multiple read replica and we managed somehow, but actually really hit our limits of expertise at some point. At some point we stopped migrating to newer database schemas because it was just such a hassle keeping availability. If I had the money as company, I guess I would have paid for a hosted solution.