You don't need an MBA to be a real estate agent, but being a successful agent requires YEARS of hard work, networking, and some degree of luck. Most people in real estate will never make as much money as a pharmacist makes. And there is nothing prestigious about showing houses all day, every evening, every weekend, etc. That's what it's like, at least at first.
I think the problem people have with your suggestion is that you make it sound like someone can say "Oh hey, I'm going to be an investment banker" and waltz into a job making big bucks. It doesn't work that way.
So please, for the benefit of all of us, tell me how someone with a HS diploma and (we presume) no useful networking contacts, or family connections, can become successful in the fields you've listed, when the vast majority of individuals in those fields never make the big time.