All economic models must involve simplifications because:

a$.$ reality is too complex to understand in its entirety, so we must reduce the complexity to a level that we can understand.

b$.$ economists would be unable to command high salaries if their models were so simple that anyone could understand them.

c$.$ they always try to duplicate all possible information and cover all possible variables that might influence decision making.

d$.$ we must rely on value judgments and ignore reality.

e$.$ human behavior is very erratic and unpredictable.