I think it is mainly because nursing isn't a 'career' kind of a job. You can make $50K an year, but 10 years down the lane, now what?
While your engineering friend is aiming to sell his start up for some millions of dollars, your job doesn't even have the scope to even attempt anything like that even if you wanted to.
Nursing has career path through specialist forms of nursing (intensive care, nurse-prescribers, etc) to management of teams, wards, hospitals, health trusts, etc.
That's what a normal career. Most people don't have the sell-the-company lottery as an option.
Actually my point was, if you look at it carefully- Professions like teaching and nursing do have a degree of career progression, but that looks super pale in comparison with any anything in the engineering domain.
The argument is similar to the discussion about Wall Street traders and Programmers. Note each of those folks at the Wall Street are taking back millions in bonuses each year. Yet we are to them a nursing-like profession, what the nursing profession is to us.
While your engineering friend is aiming to sell his start up for some millions of dollars, your job doesn't even have the scope to even attempt anything like that even if you wanted to.