Why does the threat-modelling approach assess each scenario across multiple impact dimensions — magnitude, reputation, severity, and financial impact?

Because a single incident hurts in several different ways at once, and looking at only one dimension understates the true risk.

The same breach can have a large technical magnitude, severe reputational damage (lost customer trust), high operational severity (downtime, safety), and a concrete financial cost — and these do not move together. A short outage might be low-cost but reputationally devastating; a quiet data theft might cost little operationally but enormously in regulatory fines. WHY model all four: executives weigh trade-offs across them, and regulators, customers, and finance each care about a different dimension. A multi-dimensional impact view is what makes "estimate the damage" (step 5) credible.