Thanks for the context. And yes I knew that GC riders were tough with the caveat that their physiology is unique so they can withstand conditions and circumstances non GC riders don't have the physical capacity for. But I am comparing Bernal with others of his ilk. Thanks for elaborating - I agree!I think GC riders in general are the toughest type of road cyclists. Their lifestyle demands the most sacrifices all year long. They need to be attentive and go all out basically every stage of a multi day race, while all the other riders can have multiple days off. They've learnt how to suffer the most during races.
As for Bernal...well, he is one of the best GC riders in the world which automatically makes him one of the toughest riders in my view. Then if you also consider that he excels in tough conditions, rain and cold, where the majority of riders suffer the most and if you take into account how he reacts to adversity and setbacks (in 2018 he injuried himself in a crash in Catalunya, a month later comes back strong in Romandie and in July in the Tour. Then crashes quite heavily again in San Sebastian, but comes back and next season wins the Tour. Then in 2020 he has problems with a back injury which forces him to DNF the Tour, but comes back next year and wins the Giro.)
Oh yeah, he is tough.