4 has a geometric head start that other digits don't: four corners make a stable shape. Four legs make a table stand. That literal sturdiness got folded into numerology's reading of the digit almost automatically — 4 became the number of foundations, systems, and the unglamorous work of keeping things upright.
Where 1 gets cast as the visionary who starts the company, numerology usually casts 4 as the person who actually keeps it running — payroll, permits, the parts of a life or business nobody photographs for a magazine cover.
That's a flattering story if you value dependability, and a faintly damning one if you were hoping for excitement. The tradition is aware of this, which is part of why 4 pages tend to spend extra time insisting the number is good, actually — a defense that numbers like 5 or 8 rarely need.