BlackRock return assumptions tells us about uncertainty

 

There are traders and investors. Traders take short-term risks and look for changes that will impact stocks from one day to at most a few weeks. Investors hold assets for months to years. Investors can change their allocations over short horizons, but their objective is to capture long-term premia and returns. They must think about the span of returns over years not weeks. 

The BlackRock asset assumption graph provides a good range of what type of uncertainty investors will face both for the upside and the downside. See BlackRock Investment Institute capital markets assumptions. Private equity and debt have a lot of return potential, but the risk is much greater than liquid equity and debt markets. You may get paid for the upside, but you may also lock-in downside returns. 

Don't just think about the mean return. Explore the range of returns and what will happen to your portfolio if you fall within the lower tail.