Reads like a whiner to me. Gets bored and switches jobs every two years? Doesn't want to maintain anything not written by him when he can rewrite it? These are immature attitudes. I bet his rewrites introduce a ton of new bugs because he hasn't taken the time to understand what the old thing did.
Why? I'm bored with my job. What is missed is that you get bored with a company because they're treating you like a fixed resource. You get assigned tasks in your area of usefulness, which everybody takes for granted because that's all they've ever seen you do.
You ask for time to do useful things like work on the build system or refactor some stuff to use a new language feature, but because your boss is uncomfortable letting you branch out, they ignore you. You might get assigned some busywork documentation while all the real decisions are made after hours and with no input.
Essentially, you get bored with a job for the same reasons you get bored with an SO. They slip into a state of taking you for granted.
