I believe that the pattern is a fairly pure representation of the psychology of large groups of independent speculators each attempting to act rationally trading a rapidly appreciating asset. The primary motivators of these movements are greed and fear and are fundamental to human nature. The bull run happens due to a tipping point of hype where greed and fear of missing out (FOMO) take hold and speculative fervor ensues. More speculators see this and jump on the bandwagon, accelerating the run. Eventually, the return for the initial speculators grows so large, their fear of losing the money they have earned outweighs their greed for more and they begin to sell. The price increase has been far too rapid to possibly be legitimate.