I also do not think it was limited to the gladiators. I can definitely imagine Pablo Escobar having an enemy thrown to some hippos and thinking it was "sport". That said, even the OP saying kayaking across Atlantic was something he thought about and I can tell you I would probably ride a "good" bull before that.
I do not look down on bull-riding. Very tough. Just not sure it is the toughest since we are discussing it.