It seems that many professional photographers use Nikon instead of Canon. Why?

Nikon has been making cameras. For those who know, they will know more about the camera, not only the price, but also enthusiasts and professionals will not care about the extra money. The number of cameras sometimes depends on the time period. Nikon was indeed used in the 2008 Olympic Games. Non-professionals, some people don't even know Nikon. Only they saw Canon in advertisements, and they have to say that Canon's advertising investment is very large. In addition, Canon will send many cameras to some departments for free in order to make the products have more exposure.