Back in my wrestling days, it was a good way to kind of take the pressure off yourself. It's not that he thinks he'll lose, but he's putting his mindset so that when he is in a horrible spot...it won't be a surprise to him. So when McG was using him as a punching bag the 1st round, he stayed calm and kept his composure....but when you look at when the tables turned...Conor couldn't acclimate, he knew he got stunned and immediaetly instead of keeping his calm..continued to run into Nates fire.
Kind of like GSP admitting that he was rocked by Serra, and instead of backing off and getting his composure back, he wanted to get back at Serra by hitting him...which resulted in him being finished.
Stay ready for the worst and you'll be prepared for when it happens. Fighters like Rousey who never accepted defeat fell hard when they finally met their equal.