As a self-motivated accelerator (I dual enrolled on-site with the local university my senior year of high school) I can't help but feel like everyone trying to hold me back (I was strongly discouraged) was motivated not just by trying to keep dollars in the school and GPAs they could get credit for up, but that they were also motivated by jealousy and a sense that what I was doing was somehow unfairly improving my life.
The head guidance counselor mocked me. The secretary who was supposed to buy my books and oversee my registration made me go back and forth between the university and the high school way too many times, and had a bad attitude about it the whole way.
Several of my friends who I had tried to get to follow me got talked out of it by the same people.
If it's so bad for everyone else, of course they need to come up with excuses for why it's bad for the student.
Nobody cares that these gifted students are sitting there bored. That to get an A requires them to do meaningless busywork. That the entire situation teaches them that success means showing up and demonstrating they're smart, instead of the hard work that real success requires.
Staying in that high school one minute longer, with those who were vindictive, condescending idiots, would have destroyed my psychological well-being.
My professors talked to me like I was an adult. It was very easy to respect them and my time with them. I greatly appreciated spending my time in the stacks instead of being made to run between classes all day, taking a pass to go to the restroom, and getting berated by thoughtless busybodies on my way to the library.
Our schools are first and foremost a kind of daycare that allows the adults in all of the children's lives to go to work. Only after meeting this first goal are they educational. Some schools are fortunate enough to not have discipline problems. Others are not so fortunate, and the rules and instruction is targeted to the worst performers. This greatly shortchanges those students who need challenges - challenging books, instructions, math, performance, exams, etc...
If anything, it is psychologically destructive to purposefully hold them back.