I understand in a startup that has not created revenue yet, if the “future” is predicted to be bad for the company, the value of the company only would drastically go down (for the only worth was on future hopes). However, in an established company that has made a lot of money in the past, shouldn’t all that money have been added to the value?

Imagine you were a real partner with Netflix or a similar company, and collected your share every year. You would have made lots of money in the past.