This situation is more nuanced that you might think. They are not preventing everybody from gaining access to outside ideas. In fact, they are actually encouraging their top students to spend time at elite universities abroad; they are aggressively pushing for more "partnerships" with top Western universities. Additionally, they have special Internet lines for approved entities, giving unrestricted access. In theory, selectively giving access to information this way is the best of both worlds; protecting the masses from "dangerous" foreign ideas that might challenge the Party's authority, whilst still gaining full advantage of the west's technical progress. In fact, what they've taken from the West has enabled their surveillance state. Western governments have being underestimating China for years, at their own peril. Sadly, China has not underestimated the West's thirst for money, and has used this to their own advantage.