I cannot argue against your point in facts - most will not make a real change in their lives and will be out the money they paid for whatever Ramsey thing they bought. I just bought the book.
However, I can argue in intent. I do not think his intent is malicious, just like I do not think most diet book authors are out to rip people off. Just because few can make real hard changes in their lives, I do not think the creator or a program or book is out to rip people off.
A majority of people in the US are in debt. A majority are overweight. It is incredibly hard in this culture to correct either of those. But some do. I choose to believe the most people peddling solutions do so with some decent intent. There are clearly frauds out there on both fronts.
Listened to an interesting pod cast by Dean Dwyer (has a book called Make Shift Happen, but also has a free pod) where I think he made in incredibly insightful point on self improvement books/programs. The point was that many people who are successful at something really do not understand what made them successful at that. They think they do, but it is hard to really be objective.
I have pissed away money on things to improve my health or my finances, but I do not blame any of the creators. They just did not work for me at that time. Dave Ramsey's book worked for my wife and I . . . could have been the right time right place. But it worked. The south beach diet worked for us for weight loss and lifestyle change . . . but it might have been right place right time. Both were at times we were needing change.
In the end, it is up to each person to change. No book or speech will change anything without hard work and some kind of motivation.