Career
Why career optionality is the only safe strategy
One job is a single point of failure. Most people never audit theirs.
In engineering, a single point of failure is any component whose failure stops the whole system. You find them, and then you build around them. Nobody argues about whether this is worth doing.
Most professionals have one. One employer, one income, one set of decision-makers who did not consult them about the reorg. The failure mode is well documented and everyone has watched it happen to someone competent.
The usual response is to work harder at the job, which is optimizing the component rather than the system. Being excellent at a role does not reduce the concentration risk. In some cases it increases it, because deep specialization inside one company produces skills that do not read outside it.
Optionality is the number of good moves available to you if that job ended tomorrow. It is not a feeling and it is not the same thing as being good at your work. It is produced by five measurable conditions: what your skills clear on the open market, how much of your value transfers outside your employer, what you own that works without you, how many months your savings buy, and whether you are shipping anything visible.
The useful part is that these are conditions rather than traits. A trait is fixed and a condition has a threshold. If runway is what is limiting you, the fix is arithmetic. If transferability is limiting you, the fix is external proof. Neither of those requires becoming a different person.
Most people cannot name which of the five is currently binding. That is the actual problem. You cannot fix a constraint you have not located, and effort spent anywhere other than the constraint is effort spent for nothing.