But like all hobbies, there are not necessity.
But you cannot be an engineers or medical physicians without any study, and the occupations that are necessity.
It's interesting to propose that ethics and morality are unnecessary because they are hobbies. Though I suppose it's the study of those things that are unnecessary. However, I'd argue that ethics and morality have to be taught; they aren't innate; and, they exist primarily because humans fail to act ethically and morally.
Iow, there are no Commandments (for ex) against things people didn't do. (It could be argued that the societies with the most rules/laws have the most criminals because those societies are the most criminal). God gave the Ten Commandments because the people were sinful. (And, that's why Moses "threw the book" at them).
The point is that the people must be taught right and wrong.
Anyway, about engineers, it's true they need to study; but nobody went to school to build the pyramids or the Temple of Solomon. Architecture and engineering are practical vocations. They were taught father to son or master to apprentice. It wasn't about finding a school. It was a matter of being accepted as a student. And, in my experience, most skills are learned on the job. There are carpentry schools, but you learn when you've actually done the work.
Einstein also said;
"After a certain high level of technical skill is achieved, science and art tend to coalesce in esthetics, plasticity, and form. The greatest scientists are always artists as well."
"A man is rich when he has time and freewill. How he chooses to invest both will determine the return on his investment."