Screwed by the LEA
Yes, I left Junior School (late 1970's) 3 years ahead in my learning related to my peers due to the excellent teaching of us gifted children, but this was the same year as Grammar education was dropped in my county by the Local Education Authority.
I had to go to the local (ex. Secondary Modern) now relabelled Comprehensive, whose classes in each year were labelled 'e', 'q', 'u', 'a', 'l', 'i', 't' and 'y'.
I had to sit around for 3 years for at least some of the others to catch up, and any time I showed initiative or 'extension' of the set work then I found myself on a trip to the Head Master for a caning! On one occasion when I was 13, I really stuck my heals in after the Geography teacher asked for "what do they grow in the West Indies" and I wrote a couple of thousand words on the subject of "The Socio-Economic impacts of monoculture in the West Indies" (it answered his question and a lot more around it). The Head Master actually read it and asked where I had copied it from. When I pointed out that the school library was closed at lunch time due to one of his edicts and without public transport to my village I could not access the public library and so I had no opportunity to get something to plagiarise, his smirk went, he said I should not use big words I could not understand and to put out my hand for the usual - 6 strokes of the cane. (I probably averaged 1 caning a month during my time in the compulsory 5 years of that school).
At the start of my year 5, they suddenly realised that some of us might want to do A levels and so they had to build a 6th Form Block, but even then they could not lay on even popular subjects like Geography. Unlike some of my cohort, there was no public transport from my home to the local town where the 6th form college did do Geography, so that meant a change in aspirations of University course and career.
Chip - shoulder - probably. But I made up for it once I could leave that place :-)
In my experience of mine and my children's of schooling (at least they had "gifted and talented extension work"), it is the system of political interference at all levels that is the problem and the teachers make the best with what they can.
I go into schools as a STEM Ambassador, and I have the greatest of respect for teachers and what they achieve.