Slump Dynamics and Expectation Control: A Dynamical Theory of Sustainable Success

Slumps are commonly attributed to psychological weakness, loss of motivation, or declining ability. In

this paper, we present a structural and dynamical theory of slumps based on a success index model. We

show that a slump is not caused by a decrease in ability, but by a rapid increase in expectations that

outpaces the growth rate of ability. By decomposing expectations into social and self-generated

components, we derive necessary and sufficient conditions for slump emergence, recovery, and long-

term success maintenance. The analysis reveals that humility and exposure control are not moral virtues

but optimal control strategies.