First, learning literature is much more expensive than learning martial arts. Scholars don't know how many years it will take from reading to taking the exam. After all, there are countless children in their seventies and eighties, which makes the study effort less immediate than the result of practicing martial arts. Pen, ink, paper and inkstone were luxuries in ancient times. Before the prosperity of block printing, books were hard to find, and bookcases were only available in very wealthy families. You don't need to spend a lot of money to study, learn from teachers, or take exams. Generally, a poor family may need three generations to farm to barely support a student. Of course, a poor man can be a high official, but it's hard! Learning martial arts is different. Hire a master and learn moves. As long as you are diligent enough, you can perform well in five or six years. In case of war, bravely killing the enemy will be seen by the chief. One step is not difficult.
Second, the ancient court attached importance to civil servants. The fundamental reason is that the military attache may subvert the imperial court. In the ancient and modern Millennium, every leader who changed dynasties was born in the ranks, and there was no civilian overthrow at all. The important reason is that the thoughts of civil servants have been imprisoned by the four books and five classics for a long time, and that kind of rebellious spirit is rare. This phenomenon was most obvious in the Song Dynasty, because it was Zhao Kuangyin who led the troops to shoot down the mountains and rivers, so he had to put them in troubled times and was subverted by military attache again. After many kings, most of them inherited Zhao Kuangyin's thoughts.
Third, usually the wealthy class has begun to yearn for a higher position. In ancient times, having military power was the basis for further establishing a family. Family talents with military strength? Did you sleep well? In the DPRK, for example, Xiao Shenyang's brother holds the military power, and Jiaqing Emperor still dared not touch Xiao Shenyang, a corrupt official, after he succeeded to the throne. After He Lin's death, Xiao Shenyang was robbed; During the Yongzheng period, Nian Gengyao was also armed to the teeth. During the Yongzheng period, he was afraid, so he tolerated Nian Gengyao's unruly behavior everywhere. If the rich want to enter the officialdom, they can buy officials, but if they want to gain the military power that the king is afraid of, they must make meritorious deeds on the battlefield, so the rich pay more attention to their children learning martial arts.