When u really ' advanced ' your photography skill ...... u will go for low end camera instead .. Cos u know It can produce any pic u have on mind without blowing ur pocket and tiring ur neck.
Unless u mean, advanced in term of knowing how to the camera instead of taking better photo ..
Pros can produce the pics even in the lower end cameras. The reason they like the higher end ones is that it lets them do it easier and faster.
Unless they strongly believe in "adversity builds character".