Somewhere in the business there is a single point that, if it went, would knock everything sideways. You can feel that exposure even when things are calm. Naming it is not pessimism, it is how you make the business able to take a hit.
Fragility usually hides in one of two places. Start with the one that worries you most.
When one person holds the key relationships, the know-how, or the decisions, the business is quietly fragile, and often that person is you. It is not a failing, it is just how small companies grow. But it means a single departure, illness, or burnout could do real damage. Spreading that dependency out, into people, documents, and systems, is what makes the business able to survive a shock.
If one client or one source brings in most of your income, you do not fully own your future, they do. Losing them would not be a setback, it would be a crisis. This kind of concentration is common and completely fixable. Building a more reliable, varied way to bring in customers is what turns a fragile revenue base into a steady one.