It is not overworking or overperforming in my 0.02. An ambitious American/Western European/Japanese student would rather to spend their energy to deal with real world problems because in reality, he/she may be able to get much large rewards, in comparison to ACM's award and honor.
While an ambitious Eastern European/Chinese student, the reward from local economy is worthy far less than making a big name in ACM. The same monetary reward from ACM has much higher value in those countries. Besides, after winning the award. It becomes a good add-on on resumes for applications to graduate schools in U.S. or a job at Google/Microsoft/IBM.
I am always amazed that people forget how cheap it is when you are living outside U.S and Western Europe. And the same dollar can buy much more there.
When I think about my uncle in Taiwan who have been spending 20 years to build a company that acquires 20% market share of silicone in East Asia, and its market capital is only $200 million. Any ambitious American/European hacker can make 3 to 10 millions if he/she works on the right stuffs in 5 years. Then you will know how unworthy it is to spend time on ACM competition in US but in China and Russia.