An ex of mine was a product of this. Sent off to a top boarding school young with high aspirations. With intensive tuition he achieved reasonable (not high) gcse results, mediocre a-levels and just scraped a 2:2 degree. His parents were always disappointed by his grades, thinking he should have achieved more. The facts of it were that he really was of low average intelligence, with poor executive function and critical thinking skills, and that the expensive school had worked miracles to get him the grades he got.
He struggled in the world of work, both intellectually and practically, because the jobs he was going for to impress his parents, that he was technically (only just) qualified for, were actually really out of his depth without extra tuition etc. He also had a lot of trauma from boarding school and, of course, from his unrealistic parental expectations. He was an absolute mess psychologically.
I suspect undiagnosed autism - lots of sensory issues, communication difficulties, social difficulties etc - which his (possibly also autistic) parents would never have acknowledged even if he had been able to get a diagnosis. So he was never able to be or be accepted as 'himself' as a child, and the consequences have been severe in adulthood.
I do worry about children pushed to get good grades at any cost. Yes, it might open some doors, but without a deeper understanding of themselves and a potentially artificial sense that they are 'clever' (whatever that really means) it can come with a whole host of issues down the line.