95% of internet traffic goes by undersea cable, not satellite. It's all a question of distance, and the finite speed of light. Taking the extreme case, a cable to the antipodes is about 12,000 miles. To get there via geostationary satellite needs 100,000 miles (since no one satellite, even at he geostationary height of 25,000 miles, can have line-of-sight to two antipodal points). At the speed of light, that's a delay of nearly half a second which, for modern computers, is an eternity.