Whom you partner with, how you sell and what is your expectation from a business are all critical. But there are a lot of hair extensions startups who have no idea on what the product is and they fall in trap of suppliers which are unscrupulous and purchase poor quality inventory on cheap prices. Most of these new startups end up losing customers as the hair quality is not good and customer can buy this product from Chinese suppliers directly.
If you have the right partner, who is willing to help and support you with right quality products, than only you can make money. I work with 100s of successful partners and find that key to success is in right customer service coupled with right supplier.