My daughter has an IQ of 129 which we were told is outstanding. What holds kids back from success?

teachers who think that no kid is smarter than an other and wont let gifted kids work a head as well as jobs that don't require thinking and jobs that frown on people doing things different

Things that hold people back:
•Thinking they're smarter than they really are because they rely too strongly on the terribly flawed concept of IQ tests.
•Parents who don't do everything they can to support their kids, be it reminding them to do their homework, spending time with them, or even just surprising them with a treat once in a while just for encouragement.
•The horribly flawed school system that is falling a part and does a dreadful job of properly educating anyone in anything.
•ADD. I don't mean having ADD, I mean the existence of it, because everyone just blames all their problems on ADD, whether they really have it or not, and then just shirk off all their responsibilities and go, "Whoops, must be the ADD."
•Lethargy, don't let your kids be lazy, push them, but more importantly, show them that they have to push themselves.

Several possibilities:

Things may be so easy that she's bored stiff.
If she's getting "advanced" classes, all they're really doing is pouring more of the same stuff on instead of actually teaching new or more in depth material.
She may be getting teased or ridiculed for being "too smart."
She just wants to fit in.