Most developers start writing code because they enjoy it. It is not common to find a developer that came into the field simply because they heard they could make lots of money. Working for a company writing the same boring code all the time can cause developers to want to have some fun once in a while.

When developers get bored, they come up with interesting and often overly complicated solutions that are simply not required. Sometimes, developers will come up with the cleverest solution they can figure out to solve a problem.

The problem with clever solutions is that to fix a problem, you have to be more skilled than the person who fixed it. So, if you write the cleverest code you can write, then you are no longer qualified to debug the code, and you bring your own, and everyone else's, progress to a halt.