the reason why we have to use a stop loss
1 we do not know when prices will stop and reverse direction
2 open positions we are currently exposed to SL then we can open a new position (to learn about financial management)
3 without SL our greatest risk is MC, with SL we just suffered a loss, and in my principle when we lose we can still rise more easily than if we go broke or MC
hope you understand that SL is the part of risk on trading