Why did the empire of the Great Mughals already in the XVII begin to follow the path of gradual disintegration?

It was too heterogeneous: many peoples lived in it, professing different religions and speaking different languages.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.