Complex sentence: Whereas enthusiast PCs are high-end by definition, gaming PCs can be subdivided into low-end, mid-range, and high-end markets: video card manufacturers earn the bulk of their revenue from their low-end and mid-range offerings.
Split into simpler sentences: Whereas enthusiast PCs are high-end by definition, gaming PCs can be subdivided into low-end, mid-range, and high-end segments. Contrary to the popular misconception that PC gaming is inextricably tied to high-priced enthusiast computing, video card manufacturers earn the bulk of their revenue from their low-end and mid-range offerings.