I don’t think that’s the case at all. The majority of elite gymnasts go onto study at university level. I think that often, the personality type that has the drive to become an elite athlete is the type to be an all round overachiever.
The 2 British gymnasts that stand out to me as having had a terrible education are Imogen Cairns and Alice Sumner. Incidentally both from The Academy, which has a big reputation for gymnasts going on to NCAA. Imogen and Alice are years apart in age, but what they both have in common is coming from the same area of Devon, with families who didn’t relocate to the Bristol area. They were basically sofa surfing between different families at the gym and I’m not sure if they were registered with Bristol schools at all, as that’s quite difficult to do if you don’t have a permanent address in the area. I don’t think Imogen did any GCSEs, although she possibly did them later than normal. When Alice quit gymnastics, she went to school with people 1-2 younger than her