I think work for money is extremely important for young adults. For myself, it pulled me out of a teenage depression. It gave me purpose and rewarded me not only with money, but also with a feeling of accomplishment, a tremendous amount of positive feedback from coworkers and customers, and new friendships. It builds self esteem and self worth.
Additionally, adolescence is about becoming your own person. It’s a time when we work through who we are independent of our parents. I’d argue adolescence lasts well into our early 20’s in the US. Financial independence is a piece of becoming independent.