In this case, the riddle is not referring to a person, but a company: Fairchild Semiconductor.
It took some research to verify the clues that were standing out to me, but I pieced enough together to be rather certain of my answer. Below, I don't have ALL of the clues answered.
'child' is in the company's name.
Born as the result of eight betrayals
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
I played in the sand, when everyone else played elsewhere
"Playing in the sand" could refer to the fact that silicon is used to make semiconductors. Silicon is a primary ingredient in common sand. Fairchild was focused on a different type of semiconductor than most research at the time, which could allude to "everyone else played elsewhere"
I practiced as I grew
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.
half way to becoming a maestro
I'm not 100% clear on this one.
then I became a key player in big business
They eventually would beat out all competition for their product.
my success was amplified by my logical approach
my ambition guided me, and those I supported, in giant leaps
I don't know a lot about the specifics here. I notice many references to things that semiconductors can be used for - amplifiers, logic gates, 'guide' might refer to rectifiers...
when things got too noisy I went one way
Most likely a reference to the in-fighting within the company. The Eight never really did get along with each other, brilliant though they were.
is this fair
I was betrayed many many times like my parents before me
and eventually I was no longer special
After more reading, we discover that Fairchild Semiconductor itself lost the original eight over time to its infighting... more betrayals, if you will... and quickly became a nobody in the market that it was once the king of.
A great riddle, it was fun to solve!