Careers in Mechanical Engineering is a vast field from space to land and under deep ocean waters

Mechanical Engineering is a vast field from space to land and under deep ocean waters. Some are rocket sciences and others are details of maximizing human benefits at the lowest possible cost for a one of a kind specialized unit (Tunnel boring), to many units and huge volumes of consumer items like a tissue paper.   Personally worked for a billion dollar  hydro project in the beginning, to specification of a nuclear power station, to cameras and photographic paper and films, to beverage containers and caps including medical devices such as pre-filled injection syringe.  It’s just for one engineer over almost four decades.   What are your experiences and what are your thoughts?