In terms of athletes from a young age, training hard, and often away from families to go to training centers, this is true, but one needs to understand the context within China, the opportunities that present to these athletes (pay, education, better life), and these athletes’ background (from low socioeconomic families), before passing simple judgment. I will elaborate on this below at the bottom, as I also did in comment on someone else’s answer.
These facts below however are true of why China athletes succeed at the Olympics:
1) The Chinese train harder than anyone else in the world; as other foreign coaches working with China’s Olympic Team have stated in media in past: The Guardian. Following Confucius beliefs, the Chinese believe hard work gets results, and following a progressive long-term athletic development model with repetition of technique and skill they perfect every movement until optimised (thus why they succeed in sports like table tennis, diving, gymnastics, and even weightlifting requires perfection of technique).
2) Centralised Training Program with High Government Support & Funding: The Chinese government has a heavily fund and centralized top-down training model; with the one goal to achieve Olympic Gold. The exact figures of the funding are unknown, and not as transparent as other nations, but still estimated to be the highest funded high performance program in the world. These funds help to pay athletes’ salaries, have full-time staff supporting those athletes, get the best coaches & foreign expertise to improve it further, build big training facilities, and really do anything they want. With a structured pyramid program, with around 5000 sports schools, filtering into province training centers, and then the best up into the Olympic center. Ensuring that the Chinese Olympic program can run smoothly and succeed at its goal.
3) Foreign Expertise: The big jump made at Beijing 2008 and beyond, had a lot to do with foreign expertise. The sourced the world for the best coaches, the best staff. Head coaches alone, there were 28 foreign coaches for the last Olympics; so to say Chinese coaches are “torturing” kids, then ask yourself but what about the foreign coaches? I even know examples where athletes get injured and they fly in experts from around the world for their opinions. This spending of money for an athlete is rarely done elsewhere.
4) Strong talent Identification and Long-term Athletic Development Model: At young ages they look for kids who have the physical capabilities that will allow them to succeed in a sport, and then build on-top of that strong base with a long-term athletic development plan. E.g., start with basic skills and foundation until that is perfected, then build on top of that with another skill, etc.
5) Top-down sports system vs. bottom-up: China is a top-down sports system, a system where the top level controls and manages everything with the goal to achieve Olympic success. Meaning the entire reason athletes enter the system at the bottom (the sports schools), is with the aim to achieve the government’s goal of Olympic success. Some other Asian nations however have similar systems. This contrasts however to Western nations, whereas it’s a bottom-up system, whereas the community and club levels develop athletes, and athletes enter sport for their own goals. One where they just naturally develop going through lower levels, until they have a talent, and then get recognised and selected for national program (and not until then does the government or national sports governing body have much influence on that athlete’s life). Of course arguments and debate on which is optimal. However it’s not hard to see that if you have a control of athlete’s life and sports development from the day they enter sport, and plan & goal for those athletes to succeed at Olympics, then it is much easier to plan for accomplishing that goal (in point 4 above), e.g., what education do they need, what skills do they need, what physical requirements do they need, how much sleep do they need, what medical support do they need, etc.
6) Year round structured training (More prepared): Not to say not all athletes train year round, but the Chinese have a 365 days/year training together as a team generally in most sports. Although some sports like Basketball they have around 6 months (as they spend the other 6 months in their professional teams), but that’s still lot more time together in national team than other nations. What does this mean? Well it means they are going to function better as a team, be more prepared to work with the national coach, better skilled, and better in team environment & teams culture, and with the physical resilience and technical skills to succeed. A lot of other programs in Olympic sports around the world do not follow such a professional program, for example some Olympic teams athletes train independently and then only come together to join the national team in the months or even just weeks before the games.
7) Smart Allocation of Funding: They concentrate on sports that they can win, or succeed at, be it sports that they see an opportunity (less competitive) or sports that they know they win (e.g., table tennis). For example many gymnasts are changed into snow boarding, aerial skiing, and diving. Because of the Chinese athletes’ great gymnastic abilities, they thus would make a good for a similar sports that requires these skills to help and thus can become more competitive then people without those same gymnastic abilities. They also focus on sheer medal numbers; they concentrate on sports with different weight classes (e.g., weight lifting or wrestling) or sports with more medals (e.g., swimming). But then this same approach is done by most centralized sports systems, including Australia.
8) Repetition of Skill or Technical Focused Training: the old rule, repeat until you are perfect or ‘practice makes perfect’. Very much following Confucius thinking here, in China the kids do ONE sport, and repeat the same skill over and over, day in and day out. This is something not done or rare in many nations, for example kids in Australia or America would play many sports in their childhood, they develop better motor skills and coordination but not fine tuning one skill like the Chinese. Is thus the reason China often succeed in technical focused sports like table tennis, diving, gymnastics, because they have trained until they perfected the routine. However all sports do have a technical focus, even track & field, weightlifting, and swimming; related to efficiency and ease of movement.
9) Rewards for Athletes & Better Life: The rewards for those who make it are great. Some Olympic athletes earn more a week than their poor family can in a year. That way it’s a great way forward for poor families to jump to a better social class. This provides excellent motivation for them to train hard. China Olympic champions are suggested to get $200,000USD for an Olympic Gold (figure appears to vary in different sources), and add in houses, a high level job within the government upon retirement; even winning the All-China Games grants athletes $100,000USD (depending on the province). Most of these athletes come from families that work in factories, and/or farms, earning just enough to feed the family.
10) National Pride: sports is seen as a sign of power similar to GDP. A collective culture still, looking to better the community they are within. They do it for the family, nation, and less for themselves (opposite to the west). A way to show a strong and powerful nation.
However above all, one big factor: they want it more than anyone else in the world (similar to the Kenyans in distance running), that motivational factor is big thing in elite sport.