It’s pretty well known that SAP consultants make a high hourly rate.
IIRC, Alan Weiss wrote that book back in the early 90's. BTW, Matt Inglot did a good interview with him at Freelance Transformation.
Also, I just found this article, which I have yet to read: https://www.forbes.com/sites/elainepofeldt/2013/08/31/the-as...