If it is allowed for the "who am i" to be answered by a company, rather than a person, I proclaim the answer to be: Fairchild Semiconductor.
So, I'm probably totally on the wrong path, but a lot of this seemed to ring a bell, and a Wikipedia search joggled my memory (link in spoiler, along with key points). Currently just ramblings while I try to find some smoking gun that says I'm on the right path. Feel free to comment or tell me i'm wrong :)
The Traitorous Eight is a term given to the eight employees who left Shockley Semiconductor Laboratory, to create Fairchild Semiconductor. Shockley considered this a 'betrayal'. (so Fairchild Semiconductor was "born as the result of eight betrayals") Source : https://en.wikipedia.org/wiki/Traitorous_eight "Playing in the sand" could refer to the fact that silicon is used to make semiconductors. Silicon is a primary ingredient in common sand.
The Traitorous eight worked in a garage at first, "practicing", or rather perfecting, their methods of creating a special type of transistor known as a Moore transistor. They eventually would beat all competition for this product (Became a key player in big business)
The third paragraph of the riddle has several statements that could infer various types of semiconductor products. Amplifiers, Logic Gates, 'guide' might refer to rectifiers, 'noise' is a common problem in circuits...
After more reading, we discover that Fairchild itself lost the original eight over time to more infighting... more betrayals, if you will... and quickly became a nobody in the market that it was once the king of. "eventually, I was no longer special"