Developers are like trees in an orchard

Here's a beautiful simile, courtesy of oditogre:

The programmers in a software company are like the trees in an orchard. Not only do they produce the product that you sell, but they can only be replaced by the same or a similar class. You can't hire just any ol' plant off the street, you have to get a certain kind, or you have to invest lots of time and money in splicing (training). Also, they're finnicky. They need just so much nourishment, so much space, etc. And here's one really important point: If you screw up and lose a bunch of them, they -can- be replaced, but it's going to take a while to get the replacements to the point where they are as productive as the original, and in the meantime not only will you not be making the money you otherwise would have made off the original, but you will be losing extra money getting the new one up to speed.