I actually don't think this is true. Ask Rick Lazio if being an asshole helped him against Hillary. People approach Presidential debates in a very unique way. This is an audition for one of the most important jobs in the entire world. Bluster is only going to get you so far. We can point to a million different interviews where Trump has been a complete and total mess. Polling shows us people don't think he has the knowledge and experience to be President. Him ranting and raving for 90 minutes isn't going to help that. And, ya, there's also a sexist component too. People don't like it when men act like dicks to women. I think that will be a real thread in the debates.
He has no grasp of policy and has decided not to even bother trying to git gud before the debates. He will be tripped up by something in them because you can't bullshit your way through a one v one debate.
People don't like when men bully women. We actually got a slight taste of that backlash in the primaries when Trump tried going after Fiorina.
I hope you guys are right, but clearly a significant portion of the American public respond to being a douche bag on national television in a positive way... We've never really seen anyone like him on the national stage. We'll have to see what happens.
I mean, it's not as if he's getting buried. He's still getting ~42% of the national vote right now despite the fact that he's running one of the worst campaigns in the history of the country.