Doing it yourself makes things, faster, better and cheaper than Amazon.
AWS is much easier to use than a DIY infrastructure, unless significant resources are invested in that DIY infrastructure.
Yes you can spin up a crap fast on amazon. But it’s crap and you will pay an arm and leg for it.
I don’t care about “easy” as much I care about sustainable and cheap.
Amazon RDS is everything but not crap. The great value-add that RDS provides is that they take care of all the tasks you'd normally need many days of setting up, evaluating, regularly checking they still work: replication, automated failover, backup/restore, version upgrades.