Michael Gerber opens The E-Myth Revisited by identifying what he calls the "fatal assumption" underlying most small business failure: the mistaken belief that genuine technical skill in a particular trade or craft automatically qualifies someone to successfully run a business built around that skill.

How Gerber develops this foundational diagnosis:

• He describes the common pattern of a skilled technician — a talented baker, a skilled mechanic, a capable accountant — deciding to start their own business, assuming their genuine technical competence in the underlying craft will straightforwardly translate into business ownership success
• Gerber argues this assumption proves fatal because running a business requires fundamentally different skills than performing the underlying technical work — skills in systems-building, management, and strategic thinking that technical excellence alone doesn't develop or guarantee
• He presents this fatal assumption as explaining a substantial share of the very high small business failure rate, arguing many failed businesses were started by genuinely skilled technicians who lacked the different, additional skill set actual business ownership requires

This foundational diagnosis sets up the book's overall project: helping readers, particularly those who've fallen into this fatal assumption pattern, develop the systems-thinking and business-ownership skills genuinely required for sustainable business success, distinct from technical craft skill alone.