If you have a business, your friends and family can ruin your business. Let say, you have a shop where you sell clothes. Your sister comes to your shop and wants a T-shirt for herself. Your sister may not feel like paying money in her brother's shop, or even if she wants to pay, you may not feel like accepting payment from your sister. If you are in such a situation frequently, and if do not charge money to your friends and family, or provide huge discounts, you may end up losing a lot of money.
Well, this has not happened to me because I have never owned a brick-and-mortar business. However, I do believe that if you operate a brick-and-mortar business, this kind of thing is likely to happen, especially when you are dealing with goods for everyday use, for example, grocery, restaurants, clothing stores, etc. If you have a shop where you sell computers, it is less likely that your friends and relatives will come asking you to give you a computer for free. However, they might want to get a computer on credit or for a lower price. For goods such as computers, it might be easy to deny as a computer costs a lot of money. However, if you are selling stuff that does not cost a lot of money, it might be difficult to deny.