My daughter was GT from the 5th grade. I have no idea how I got in, I didn't know it was a thing when I applied. My grades were average at best.
The only reason I had Advanced classes was because I was bored in regular classes and became a distraction. I assumed my daughter was in without issue, if that's what she wanted. My sister got a BA and PHD from UT, dad - masters, with a phd, and daughter graduated with a 4.3 GPA with a year and a half of "college credit." - Also, 120 other graduates in her (affluent) HS graduated with 4.0 or better.
She had to CAP. We were looking at 4 decimals trying to know. Had offers for out of state "for 3 times tuition at name brands" at good schools, free or subsidized at Ark, Ala, Baylor, but she wanted UT. Luckily, the last CAP segment through UTSA.
Admittance is either "Connected a big way - not 2k a year connected," "crazy brilliant," or "Grinder." - no homo.
It sucks that smart, connect-the-dot people go through this and find the rug pulled out from under them. Admittance, value of a degree, you name it. It's not clear for lots of folks. It is what these kids and families think. Most of the wealthiest people I know are not "professionals." They are people who think. Hard. Differently. But they effort. Harder.