There's two factors going on with the P38-
There's simple utility- aside from the 101 uses people find for it (and it takes practice for a few weeks to think of it being there- like anything, once you get used to grabbing it you value it more)- combined with the light weight, durability, and elegant design.
Doesn't mean everyone will love it, but the majority of people who experience them (especially with 10 minutes of mentoring) keep them around.
But there's another side to them- a mystique that makes them worth a bit more in some ways. I can't explain it better than the following, so I'll just post this:
Here's an excerpt of an article- a letter by "digger" sent to georgia outfitters.
"After college and a degree in philosophy I enlisted in the U.S. Air Force on 2 July 1976, looking for something that college could not provide—direction. I quickly adapted to the discipline offered by the military and the growing fraternal bond that military members experience. After our third week we were marched off to the M-16 firing range for two days of dry- and live-fire training. Our mid-day meals were c-rations which proved to be my life-long love affair with scrambled eggs and ham (I’m not kidding…I really liked them…couldn’t stand the beef stew though). Included in the case were a number of little packages bearing can openers that I personally thought were somewhat cleverly developed tools. It was very interesting watching guys investigate these little contraptions. While eating we were joined by a couple of civil service engineering guys working on the range infrastructure who later explained had been in Vietnam in the early 70s. They (and the TI) showed us how to use them. One of them named Steve picked up the P-38 next to my boot and said this was the most practical thing the U.S. government had ever produced because it was made exclusively for the GI as a personal item to be carried through all sorts of circumstances. He handed it to me and said “Put this on your dog tag chain and keep it there. It’ll survive a nuclear blast.” He then showed me his key ring and the two he kept from Vietnam . He said “This will be a constant reminder of where you’ve been and your time in the military.” Like some mentioned on your website, he used his to adjust the carburetor on his vintage GTO.
I took Steve’s advice and kept it on my dog tag chain. It went with me to security police air base ground defense training, my first duty station at Pease AFB, heavy weapons training at Camp Bullis and Fort Hood , my remote tour in Korea , the somewhat quiet 80s, the Gulf War, Balkans, and all the peaceful times in-between. During the peaceful periods it was with me on my key ring. The P38 now graces my silver necklace given to me by my family in the mid-90s.
Along with my wedding band, my U.S. Shelby Co (with the little arrow thingy) P-38 is my most treasured piece of jewelry. I wear it permanently on a silver chain my wonderful wife and children presented me over 15 years ago. But why is it treasured? I’ll try to explain.
Military folks have a special bond. We may be different in terms of personality types, genders, ethnic backgrounds, and so on, but we all served. And we served for reasons beyond ourselves. That’s what makes military folks so special. This little non-descript item called a P-38 is that little, personal item that was considered one of life’s little luxuries that, in many regards, provides us with a sense of identification when the world wanted to identify us by our skin color or religion. It’s similar to the dog tags, but it goes beyond the “meaning” of a dog tag. It is almost a fraternal symbol of sorts, one that is instantly identifiable by veterans that used them. My Shelby Co. P-38 also reminds me, every day, of my service, and I cherish it along with the flak vest my mortar team signed while in Korea . Unlike jewelry (and the current infatuation with “bling”

, jewelry calls attention to itself as a validation of “self.” A P-38, in its non-descript form, is recognizable by those that served beyond “self.” I suppose our P-38s are more than symbols of a time gone by. Our P-38s remind us of us. I have had several people ask me why I wear a silly little piece of stainless steel on my silver chain. More than once I have tried to explain, and have even grown a bit quizzical myself as I try to explain. More often than not, I stop, smile, and say, “Well, if you have to ask, you really wouldn’t understand. It’s a bit silly, but you can’t really appreciate how special it is until you’ve used one under adverse circumstances.” It’s not that we’re trying to be exclusive, but a civilian has a difficult time understanding what some of these little mementoes mean because they simply do not have provenance (context) with a specific event/place. Civilians (except for our awesome police, firefighter, and government peacekeeping corps—FBI, homeland security, etc.) rarely have to deal with dire circumstances that deal with the management, delivery, or receipt of deadly force. However, when a fellow vet from the 1940s to late 1980s views it, the conversation usually starts with “Man, I used mine to do (you fill in the blanks because the stories are as varied as they are interesting)”. They then usually end the conversation with “Man, I wish I’d kept mine. It was one thing in this world Uncle Sugar game me that meant something to me.” However, another phenomenon occurs, a phenomenon that seems to occur with military folks. They usually connect the P-38 in context with other people and events under somewhat dire circumstances. Again, it’s hard to describe, but the P-38 (like the C-Rat spoon) my not just be the best thing the U.S. Government provided us, it may very well be the very best part of us who, as generations of citizen soldiers, have a small battle-scarred memento that reminds us of the days of our selfless service, adventure, and friends who departed defending their buddies and country. One can’t really carry around a Jeep or a grenade. But one can carry their P-38 (and their C-Rat spoon). In museological terms, the time-place empathy theory really abounds here because the P-38 is an artifact with context and personal context at that. Just watch/listen to any vet when they view the P-38. Complaints of how much they hated C-Rats will probably be the first comment, but they identify with the P-38. Again, social scientists and psychologists will have a difficult time with developing a theory. That’s because the P-38 represents the best of us all—our humanity and soldierhood."
For people not in the military, it can be symbolic of a relative, or even the old american ideal of Doing Stuff- you might miss out on the "Unofficial challenge coin" aspect of it, but it's a uniquely american icon, and ridiculoiusly useful.