But with an autoscaling group a new one magically pops up in the same AZ if an old one dies. You don't get that by rolling your own rack (without having hot spares on hand, in multiple racks or data centers). Not to mention getting a managed SAN basically for free (EBS) and backup/restore, and managed DBs... I'm a pretty good engineer, but I'm not good enough to be an expert at managing racks of hosts, switches, routers, storage, tape robots, databases, etc. And I don't have to be with cloud services. I just press a button and it's all there.