A co-worker used to ask, "did you make something you can drop on your foot today?". Making or doing something tangible, something that you can see and touch, can be very much more satisfying at the end of the day than say keying data into a computer all day.
Another angle to consider..... I saw a study many years ago talking about fatigue and stress. Even though a tradesman works hard (think welder, construction, etc...), it's a much better kind of tired than someone who sits all day. Generally healthier and happier.
Regarding the first part of this conversation, I sort of think it a mistake to set sights on a string of merit badges that align with a boy's career goals.
He's a kid, what does he really know about what he might want?
Sure, work on those that fit within the path he thinks he wants to take, but encourage him to take others as well. He may find other interests for either career or hobby.
Also, the whole scouting journey could be looked at more like college is in many ways. It's not so much about learning specific skills for a specific job, it's really more about learning how to be trained and proving that you can be trained, learning critical thinking, learning basic things such as communication that help no matter what path you end up on.....