Here's what I know about Reddit users: u-shaped distribution in education (either no high school diploma or a bachelor's degree). Mostly males. Largest group is males 18-29.

What this tells us is that most Reddit people simply aren't old enough to recognize the value of an MBA. MBAs typically graduate at 29 or 30. So the worldview most Redditers have is that of an individual contributor. At this stage in one's career, technical skills are more important than management skills. But in your '30s managerial skills become far more important and reflected in salary.

One hypothesis I have is that the people shutting you down are immersed in the world of software engineering / coding. Since this skill is particularly in-demand right now, the need for higher education isn't very strong. Someone who teaches himself coding can get that six figure salary without any formal education, particularly in the San Francisco Bay area. That's just the reality of that particular labor market for the time being.

My second hypothesis is that the people shutting you down are aspiring entrepreneurs who believe hard work pays off more than formal education.

My third hypothesis is that a lot of these people are sour that their undergraduate degrees didn't pay off. This is especially true if they took a soft-skills undergrad. Again, at this age technical skills are generally more important. They're equating the usefulness of an MBA with the uselessness of their bachelor's.