You're an idiot. I'm glad it sounds dumb to you. Stay away.
I just googled slab city, and the wiki is the first page that comes up, which tells it pretty well, but since you seem to have some problems reading, here is my take on it:
Slab city was a military base, that was shutdown, for whatever reason. The military took all of the metal, leaving behind a lot of big concrete slabs. The salton sea was formed, tons of people started building resorts around it. The state of california gave the old abandoned military property to the california teachers union, with the thought that the property value near the salton sea was skyrocketing. The salton sea was stagnant, everything died, all the resorts being built went under before they were even finished. Slab city was wasteland, worth nothing but a tax write off to the CTU.
Around this time, people started moving in, and squatting the place. There is not so much reason to, other than the fact that it is a huge piece of land, warm enough in the winter, and quite isolated. Everything surrounding is millitary bases, small towns, abandoned resorts, and large farm industry.
As far as why traveling kids like to go there, I guess probably training to go to alaska.
For me, it was like some crazy post apocalyptic dream. People living in total anarchy, more or less untouched by the law. You didnt fuck around, or you would end up getting shot, and buried in a shallow grave somewhere in the desert.
The place is full of all of societies rejects, from outlaws to veterans to old hippie burnouts. A lot of these folks have no where else to go, and I guess most of them will die in the slabs. It's not really a place that is "made" for travelers, nor is it a gentle easy place to get by as some scumfuck. If you are fucking hardcore, and can survive living in the desert, miles from any real supplies, this is a great place. You can do whatever you like here, and there is a good chance that people wont be against it. I dont mean you can be a stupid drunk asshole, but if you want to build a home, live off the grid, make a real life for yourself, this is the perfect place.
Not your typical retirement community, but I guess you probably havent read this far, so better you just stay home.