Passive investing when you have many years before retirement means you worry about long term trends rather than short term risks.
Whereas (more seriously) investing in "more stable" things like bonds forces you to pay a premium, because every man and his dog has desperately been chasing stability, safety, yield, etc since 2008, in many cases using quantitatively eased money to do so.
When a thread takes a turn for the worse, please don't reply unless you can make it better, not worse still. Political name-calling makes it worse still.
Since I had to ask you to keep partisan politics out of HN threads only a couple days ago, I'd like to emphasize the point. This is not what Hacker News is for. Please (re)-read:
All the code is in the same repository as R Markdown.
SPY / VFIAX / S&P 500 has a CAGR 4.9% from Nov 2000 to Nov 2016.
"The average 30-year rolling total return for the S&P 500 starting with 1926, is 2,478% or 11.21% annualized (geometric mean). There were several 30-year periods that had annual returns between 8% and 10%."
Having said so, past returns don't guarantee anything for the future. They might give you an indication though.
Edit: Here's  a better (?) graph of the S&P 500 with the 30 year rolling returns, inflation adjusted and dividends reinvested. Source