Why do 6 year olds still suck their thumb?

Six-year-olds may continue to suck their thumb due to comfort and self-soothing, as it provides a sense of security similar to when they were younger. It can also be a habitual behavior that has developed over time. Stress, anxiety, or changes in their environment can further contribute to thumb-sucking as a coping mechanism. While most children outgrow this habit naturally, some may need gentle encouragement to stop.