Not sure how widely it is used, but the term “tall poppy syndrome” comes to mind when I hear/read about people like those you describe. You dare to grow that little bit taller, and get your head out above the rest, some jealous bastard will cut down the tall poppy! It ends up being a device for maintaining mediocrity, as the cutters try to keep others at their level (which is often relatively low). Well, screw them. They can’t cut everyone down. Keep growing! Be the tall poppy. Be the emergent tree in the rainforest. Let the poppy cutters be the slime moulds that they reveal themselves to be. [Actually, slime moulds are quite interesting in their own right. Maybe use another term … ]