Three ways to make money:
1) trade time for money
2) trade money for money
3) trade other people's time and money for money.
Working, consulting and personal portfolio management fall into category 1.
Bonds, GICs and bank interest are in category 2.
Stocks, mutual funds, index funds and owning a business are in category 3.
Category 2 has historically returned the lowest returns. Does this make them lowest risk? I don't think so. Yes your principal can be protected if you always hold until end of term. But your buying power has eroded and you have made less than both other categories most of the time.
There has been substantial debate about Category 1. I believe that those who risk their egos the most (such as in sales or as CEO) get the best returns for their time invested. They risk personal humiliation and public failure more than most employees. This is the single highest leverage that most people enjoy during their first 10 years of career.
Category 3 is where most people discuss risk. I have seen discussions about tolerance for volatility as the most productive as the determining factor for what kind of returns one can hope to make. Just look at the 12 month stock charts for individual companies to appreciate volatility.
My father, MIL and brother have only invested in Category 2 and this has cost them dearly both in their working and retirement years. Their only source of speculative returns has been their property purchases.