There are. I've had the misfortune of working with people like that frequently. It leads to a lot of frustration, because they tend to write very verbose and convoluted code with very little documentation, so in addition to performing poorly, it's a pain to read and debug.
Naturally, they aren't up to the task of debugging their own code, let alone optimizing it...
Naturally, they aren't up to the task of debugging their own code, let alone optimizing it...