savings accounts are very safe and secure and should yield around 1% on average.
US treasury bonds are also very safe and should yield around 3.5% on average.
An index fund tied to the S&P 500 has yielded 9.7% average over the last 90 years. It comes with higher risk and volatility.
Savvy investors strive to beat the S&P 500 by investing in riskier, more complex or higher cost investments like real estate and expect returns of around 12.5% or better.
