MBAs probably make good money for themselves. I don't think MBAs make money for the organization they are in. Any organization that has a large influx of MBA managers (replacing people actually competent and willing to do real work) begins to drown in procedural morass and a sea of paper shuffling. A fantastic example was Dell. It was completely taken over by the consultants from Bain, who ran the company into the ground. Google is the next example - it has been named as "most desired place to work" for MBAs, ahead of Mckinsey and Goldman Sachs. Luckily they had the common sense to insist that their CEO will be a person with scientific education, rather than merely bean counting, oops, MBA education.
The problem with a lot of MBAs - they are often competent enough to be useful members of society, but instead prefer to not do anything with their abilities. The confidence projected by a typical McKinsey consultant stems from their arrogance at being in McKinsey, not from their knowledge. One such person I met even went so far as to admit "I did a Phd in Philosophy and had no career option except to be a Management Consultant."
Jim Simons who is probably the most successful and richest hedge fund manager has started publishing papers in topology once again, at the age of 60. On his deathbed his main concern will not be that he did not do an MBA.