OK, let me get this straight. Pope Benedict has the absolute easiest, softest job in the world and he thinks its too hard, so we wants to resign. I mean, let's get real, how hard is it really to be the Pope? Is holding your gold and jewel encrusted scepter really that tough? Does wearing the goofy hat make your neck muscles hurt? Is it that hard to live in palaces filled with priceless artwork and sit on the softest pillows atop your thrones and pulpits?
You are basically a king -- one of the last divine right monarchs in Europe -- and have people to do absolutely everything for you including wipe. That's why nobody has resigned the job in the last 600 years.
Now, I know people are still going to say that it must be "stressful" and compare it to being President of the US (POTUS), or some other head of state. However, really, it is nowhere near as hard as being the POTUS. For one thing, they can't vote you out of office no matter what you do. Secondly, you don't have to convince anyone of anything. It might be like the Supreme Court, but there is only one of you, and your word is law. Plus, your decisions don't have to make a lick of sense. In fact, it's better if nobody understands them.
You ain't gonna find an easier or better paid job, and it's not like Benedict had a lot of other marketable job skills.