What happens if you leave acne untreated for too long? is that how scarring happens?

Normally: Acne scarring is a complex skin reaction. To leave an inflammed lesion for a longer period of time is more likely to scar, but sometimes the depth of the inflammation or its intensity are also factors. There is also considerable individual variation in who tends to scar. As a rule, it is better to have the acne treated as soon as possible.