The challenge lies in trying to be above average in assessing the future. Why is that so hard?

First of all, forecasting is a competitive arena. The argument for the difficulty of out-forecasting
others is similar to the argument for market efficiency (and thus the limitations of active
management).

• Thousands of others are trying, too, and they’re not “empty suits.” Many of them are educated, intelligent, numerate, hard-working, highly motivated and able to access vast amounts of data and computing power. 
• So by definition it shouldn’t be easy to be better than the average.

In addition, since economics is imprecise, unscientific and inconsistent in its functioning,  there can’t be a method or process for forecasting that works consistently. 

• To illustrate randomness, I say that if, when I graduated from business school, I was offered a huge budget, an army of PhDs and lavish financial incentives to predict the coin toss before each Sunday’s football games, I would have been a flop. 
• No one can succeed in predicting things that are heavily influenced by randomness and otherwise inconsistent.

So forecasting is difficult for a large number of reasons, including

• our limited understanding of the processes that will produce the future, 
• their imprecise nature, 
• the lack of historical precedent, 
• the unpredictability of people’s behavior and 
• the role of randomness, and 

these difficulties are exacerbated by today’s unusual circumstances.

Reference:

In investing, uncertainty is a given – how we deal with it will be critical. Read Howard Marks’s latest memo, in which he discusses the value of understanding the limitations of our foresight and “investing scared.”

https://www.oaktreecapital.com/docs/default-source/memos/uncertainty.pdf