The last time I compared hosting prices of AWS with self-hosting. AWS based hosting would have cost us every three month the cost of buying over the top speced server hardware. These numbers are not directly comparable, but they are a large difference to account for colocation and maintenance. And we never managed to get a similar performance of postgres on AWS compared to the self-hosted version we use now. But the main advantage is the simplification you get. It is certainly not easier to use you own hardware, but it is far simpler.