First of all, there is no doubt that mathematics exercises people's thinking ability and logical ability. Olympiad Mathematics is the extension and expansion of learning mathematics in class, a deeper understanding of some theorems and an active exploration of some mathematical theories. If the mathematics in the classroom is extensive, it is no exaggeration to say that Olympiad Mathematics teaches the essence, and everything is sometimes inferior to anything. That's the reason. I believe you have experienced so many things and gained some understanding.
Secondly, in the process of learning Olympic Mathematics, your child's experience of continuous thinking and exploration has been exercised. The more you use your brain, the smarter it will be. More importantly, many methods of Olympic mathematics are often not so traditional, and sometimes the way to solve problems is opportunistic, and all kinds of coincidences can get answers. This model can help children avoid sticking to the traditional way to solve problems. Divergent thinking is strongly stimulated in the learning process.
Thirdly, the competition for social talents is becoming more and more fierce. More and more parents enrolled their children in various talent classes and Olympic math classes when they were very young. Personally, I don't agree with this kind of move, but since this kind of thing has happened again, to put it bluntly, I don't study and lose to others at the starting point. Olympiad is not a gift, but a personal ability. It is necessary to learn a little.
Finally, learning Olympic Mathematics is a good way to spend your free time. Nowadays, communication is more and more developed, and the phenomenon that teenagers are addicted to the internet and mobile phones is very serious. Giving lessons to children not only reduces the time for self-discipline, but also allows children to spend more time with other children. After all, the only child is sometimes lonely.
All the premises are that children don't hate it. It's good to go to school. Not going doesn't mean they must fall behind other children.