Price difference between Nikon and Canon super telephotos
I am starting to learn bird photography and currently use 70-200 F2.8 VR with a TC-IIE. Obviously, the range is limited and sharpness/foucs speed are not great. In not so distant future, I see myself going for a 500 F4. However, there is a huge price difference in the equivalent Nikon and Canon lenses in this range, and sometimes I wonder whether I should switch to Canon. At the same time, I would really like to avoid the hassle of selling my current gear.
My question is how do Nikon users justify the higher cost of Nikon super telephotos vs. those of Canon? Thanks!:)