You have real and honest outlook on investing. First step is not to loose money, so we look at inflation and at 1.5% (guess-tamate)....... Anything over that and we're making money.
8% is just unrealistic or unsustainable when the GDP is 1%/year.
The ROI should be more of an n% above the Federal Funds Rate...Which is now about zero...I think 3% above the fed funds rate is a reasonable expected ROI...