Why would you assume that because someone doesn't have a family, they would prefer to eat fast food or out at a restaurant? I don't have a family and have cooked all my life. Sure, it might be faster, easier and make less of a mess (other than take out containers, of course) to eat out, but who wants to do that every day? It's also very expensive. Eating fast food on a daily basis is not healthy, and it's best left to an occasional treat. Many people of all situations prefer to cook their own food these days, so they know where the food came from, and what is in it.
Home cooked meals are so much better then fast food meals. You know exactly what you put in it but you can adjust it to your liking and taste. You can cook a bunch of it and have it for a few days a week or freeze some of it and have it at a later day.
Besides the fact that you can cook more healthy food at home, it’s about 2 times cheaper and some people really like it ... Some people have to cook on their own, for example, due to allergic reactions to some products. And not all restaurants are ready to talk about the full composition of their dishes.