I am one of you and have no idea about how stocks work so I had to research exactly this question:
"What happens if the market is full of monkeys that drive a company like MU down to p/e 1 and stay there and they are selling into huge earnings and estimate beatings for years"?
So the question is not simple. You don't automatically lose because the value is depressed.
* The company can do buybacks. These decrease the number of shares floating in the market and usually it drives the price up because of less liquidity
* The company can pay big dividends. Even if the buybacks don't do much, they increase your relative ownership of the company which means you get bigger dividends that at some point would be big enough it would be a no brainer but we are talking about no-brain retail market here so read next point too
* Eventually you would be owning a bigger % of a production machine of the real gdp economy. This would be temporarily dettached from your nominal amount you see on your dashboard. You will in theory have less money than someone else but you will have increased your actual % of ownership in the global market more than him. These two things will eventually and painfully catch up because of the power of the first 2 forces.
Right now there are some companies they could buy up all their shares in a couple of years earnings.
*That means that both the market can stay irrational, and you holding can gain even if the stock temporarily goes down. If your % of ownership of a very profitable company goes up, price doesn't matter for now.*
Now it's up to you to sell and short the most profitable companies ever to oblivion.