Shampoos are designed to cleanse the scalp and hair by removing dirt, oils, and styling products. They contain cleansing agents called surfactants, which can strip away some natural oils. While this is necessary for maintaining scalp health, overusing shampoos with strong surfactants or sulfates can lead to dryness and potential weakening of the hair strands.

Using shampoos in moderation shouldn't make your hair weak. However, excessive use of harsh shampoos or not properly rinsing them out could potentially damage your hair over time. It's important to choose a shampoo that suits your hair type and to follow a healthy hair care routine.