The associated beliefs come from some quotes such as :
"if you want to earn higher returns, be prepared to suffer grievous losses from time to time. And if you want perfect safety, resign yourself to low returns. "
This belief of high risk = high return will lead to the belief
"best way to spot investment fraud is the promise of safety and high returns. If someone offers you this, turn 180 degrees and do not walk - run".
Others quotes
"high-risk societies - or crisis periods in stable societies - result in high investment returns- if those societies survive".
Here the high-risk is synonymous to high volatility.
Aka high risk = risk in high volatility environment = higher rewards...