you can measure how risky it was using something like Sharpe Ratio. Then you can assess how likely you are able to repeat it again. Also, kelly criterion allows

you can measure how risky it was using something like Sharpe Ratio. Then you can assess how likely you are able to repeat it again. Also, kelly criterion allows you to measure risk of ruin for every bet. "making consistent returns in 4 years" does not really mean anything without additional information.