Bull, Bear and The Pyramid

Read ? Portfolio Management - Your Personal Over-Sold and Over-Bought Indicator - Revist

We often hear this:

"Bulls climb up a wall of worry, bears slide down in a slope of hope ."

Why must the bull climb up a wall of worry?

The bull should stop climbing the wall of worry but climb the wall of the Pyramid.

The layer of Pyramid represents the level of stocks that the Bull should be holding when it climbs the wall of Pyramid.

Similarly, why must bears slide down in a slope of hope?

The bear should just slide down the slope of inverted Cash Pyramid.

The layer of Pyramid represents the level of cash that the Bear should be holding when sliding down the inverted Cash Pyramid.