This is different though - the gimlet podcast is about dropshipping, where you don't keep inventory and are literally just creating a sales pipeline for someone

This is different though - the gimlet podcast is about dropshipping, where you don't keep inventory and are literally just creating a sales pipeline for someone else, and absorbing all of the marketing costs (hint: why would a manufacturer / wholesaler let you do this for them if it was profitable?). In this case you're entering the supply chain of a product (cut fabric), which end customers cannot do for themselves and wholesalers cannot scale.