As to your "Why do people pay them?" question, companies get to the scale where managing their servers in an automated fashion is necessary, and deploying new boxes within a matter of minutes instead of hours is critical. As a DevOps guy, our job is to always automate ourselves out of our job. Why do I want to do anything more than once? Deployment tools like Chef and Puppet help with the "Don't Repeat Yourself" concept.

Disaster recovery is another area where these tools can help. Imagine your database server goes down. Downtime can be really expensive, depending on your application. With Puppet / Chef and an interface on top, you could click a button and have a new box spooled up and your data automatically restored from your most recent backup. Downtime would be reduced pretty dramatically.

Auto-scaling is yet another possibility; if you can detect when you need another server, you could script it so that another server gets reserved and deployed and brought up to snuff. Then, when your traffic drops down, you could release the server.

At some point, it makes sense to either hire a DevOps guy, and / or spend money to have the deployment cycle consistent, dependable, and repeatable.