I would argue not that the planet is over populated per se, but that it's over populated by idiots. Sure, we all make mistakes at one time or another, but there are people out there who continuously make the same mistakes over and over and then have the nerve to compound that with new mistakes and yet never think they're doing the world any harm.
I'm not saying people need to be scholarly, though it can't hurt, but is it too much to ask to have a modicum of common sense and street smarts?
One could argue that the silver lining is that an idiot will at least find new and interesting ways to end their life and thus do the world a big favor, but the flaw in that logic is that those same idiots usually end up taking a smart person (or at least someone with potential) or a group of them along for the ride.