I personally think China's build up of infrastructure and troops on the border with India has two-fold primary benefits for China, both in building up much needed roads and rail links in these remote regions, and secondly, it preoccupies the Indian Government and its resources into spending more on defence, when money is actually more desperately needed on domestic infrastructure, hence China can influence (stunt) India's development just by posing the threat on the border.
You are probably asking, well aren't China using up resources on the border too? Which obviously they are, but the huge difference with China is that she can afford the build up. China is a far bigger economy, it's far more developed infrastructure-wise already, has far greater capacity and expertise in building large-scale infrastructure projects, so can build roads, rail and bridges far more efficiently and cost-effectively, and all necessary military hardware is almost exclusively made indigenously and at a fraction of the cost at which the Indian military spends on overpriced foreign weapons of similar capability.
China knows a strong military is based on a strong economy and if she can stifle India's economy by diverting money to expensive defence expenditure instead of improving India's industrial base and domestic infrastructure, then China can successfully hinder India without actually having to attack India. China are masters at this kind of strategizing but I think most Indian politicians are too short-sighted or maybe oblivious to China's ulterior motives in its border dispute. I'm guessing many Indian politicians do know but are happy to pander to popular public opinion and buy more warplanes and ships, as this makes the average Indian feel more safe, while officials are more than happy take their cut of weapons deals.
I don't think China has any intention of attacking India. China just has to make it look like she might. Of course, arming and supporting Pakistan further advances this cause too. This is just my personal view on how I see the ongoing border dispute.