ADC is THE most tilting position, followed closely by jungle
Why? Because as ADC you need help to accomplish anything meaningful.
You need a support in lane, you need a front line in fights. You need your team to help you push objectives.
In the random queue, you'll run into tanks who hide behind their backline, tops who immediately back after winning a team fight instead of pushing an obj and supports who kill themselves multiple times in lane and don't ward.
All this means: getting fed on an ADC is not a win condition provided you don't have teammates willing to support you properly

typically need your team to not be losing, because even if you're fed, your power is late game, not mid game.