If you lower the neck of a bottle with water into a vessel with water, then water does not flow out of the bottle. If you put a sheet of paper on a glass of water, press it with your hand and then turn the glass over, the sheet of paper will remain in place and the water will not flow out. This is due to the effect of atmospheric pressure.
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.