He saw that his power won't necessarily bail him out against elite fighters. The look on his face when Fury got up was priceless! And then he went at Wilder guns blazing (relatively) and had him hurt. Joshua also got up from a big right hand from Klitschko, although he went to full on defensive mode right after. But he still got up. I wonder if he will lose some of that confidence now.
Just as ****ed as Vlad is , even to this day Tyson gives him nightmares. 'How can someone this slow , not so strong and looks like a plumber beat me ??!! Because you cannot hit him...
It really, really sucks to hit a guy with your best shot (especially once you're tired and gassed) and he keeps fighting. Not a pleasant feeling.