Why do adults love to praise other people's children and then say that their own children are not good at anything?

For such adults, in fact, they do not think their own children are not good enough, but because they themselves do not like to show, so it will cause such a status quo.

But in the face of why adults like to praise other people's children, mainly because in the eyes of many adults, always like to take their own children and other people's children to make comparisons, so there will be a certain gap.