Lots of cash doing nothing on the sidelines is risky in the long term because inflation. A "risky asset" is risky in the short term because of volatility.
It’s completely different. The acceptable risk profile changes depending on a lot of factors, not only returns on investments. Someone holding on NASDAQ in back in the day would not see their investment go back to 2001 levels until 2016. That was quite a deep hole to climb out of.