Ok presuming OP isn't just having a dig at people who think their child is gifted...
I'll answer from the perspective of an adult who grew up fairly gifted and has reach some spectacularly dizzy lows.
The point is, that if a child is gifted, they will have a need for extra support and also (unbelievably) protective strategies to prevent nastiness and bullying from among others, their teachers, from making their lives a hell on earth.
I was bullied by teachers and regarded as strange by other children. I was pushed into performing while all the time being utterly terrified of it - this compounded the stress tenfold.
I dropped out of school after consistent underachievement, and my projected 'career' never even started...here I am at 35 on benefits with two small children and no husband, no job, no confidence.
And I still get bullied for being too clever.
Do you see where I am going with this? It's not just a showing off thing, being gifted, It's a condition and unless you have adequate support you are looking at a lot of unhappiness.