Challenge is one thing, stability is another. While it was true that OC implies instability and/or premature deaths of parts, consider these. I have systems that were scrapped due to age. I have no systems that died due to OC. I have lots of fans. I have killed lots of PSUs. I have seen mobos die under normal use. I have seem drives die under normal use. I lots of old video cards that just won't die. I OCed a 8800GTS until it is not stable, meaning scrambled graphics (artifacts) than back down 15 Hz. Try to utilize it as much as i can, until it is not even worth it to be plugged into main systems so I have it on folding 24/7 for 2 years and it still won't die! Many 8800GTS complain about it dying without OC. Why?
Once you started with OC, assuming you don't simply clock it mindlessly, you will learn how to properly maintain a system, both hardware and software level. It began with small window tweak and mild OC, and then people will eventually go into different ways. Some aim for silent build, some aim for suck looking build, some aim for least maintenance, some obviously love speed. Like s1njin said, it isn't about the final clock, but the journey towards it. At the end, some more hertz, lots of knowledge, and a good night sleep feeling you have just got something out of nothing.
Most who OC test their system with stress programs for hours, some do it for over 24 hours to ensure heat is radiated properly to ensure stability. They know where the boundaries of their system are because they have touched it, tried it, and tested it. They can tell you what their idle and max temp is without starting their PC. Some even know the frequency, voltage of CPU as well as the timing and voltage of RAMs. Their system is by far more stable than most people who buy and assemble their computer. Some can even fix problems for others simply because they have learned so much through the process of OC.