We build world views like we build houses: brick by brick (or opinion by opinion), over the course of time. We use pieces that match and fit well together. If we are a good builder, our house is comfortable and strong.
A debate is like trying to convince someone their house is built poorly. The more fundamental the debate, the closer you get to the foundation of the house. The big debates are all about foundations. No one wants to tear down their entire strong, comfortable house because the first course of bricks is drawing criticism. It is a phenomenal amount of work, requires destruction of something you love, and leaves you without shelter in the interim.
Hence, people rationalize the work they have put in, saying yes, there might be flaws, but it is otherwise strong and serviceable. In fact, it is a well-constructed as any house out there. Better, in fact, because it suits them. Other people’s houses are strange and uncomfortable, so where is the impetus for change?