Econ is great at predicting the future. Let’s say your uncle tells you about his new stock trading strategy that’s guaranteed to make him 10% returns per month. Will he be rich two years from now? Econ’s efficient market hypothesis predicts he will not.
Or let’s say the president of Japan announces a plan to beat deflation once and for all. He says that next year, he’ll fire their central bankers and hires the ones from Venezuela, give them a 100% annual inflation target, and promise them millions of USD in bonuses if they meet or exceed that target.
Even though this plan is going into effect next year, what will you see the next day? (Assuming people believe the president is serious.) Econ predicts you will start seeing inflation immediately. And we see effects like these all the time when looking at how the actions of central bankers effects the economy – if Powell says he’s going to change interest rates, there’s a reaction in the markets when he makes the announcement and not one when he makes the actual change.