Fast Fashion includes the process of mass producing clothes in an often unsustainable manor. It uses up valuable resources and causes damage to the planet (deforestation and habitat destruction, water and air pollution, etc). Millions of clothing items go to landfill each year, totalling to hundreds of thousands of tons of fabric waste annually.
When members of the public buy into Fast Fashion, they are supporting unsustainable practices in a vast number of ways. The money goes to help fund these factories and shops that sell the clothing, and hardly anything gets paid towards the labour that went into it.