Do I make my own bread? Sure, sometimes I do. Baking bread isn't that hard. But do I do it every day? No. Why? Because it takes time to do, my kitchen counter is usually a mess afterwards, and the result usually doesn't taste anywhere near as good as the 20+ bread varieties I can buy at the corner store. I sometimes do it for fun, but I wouldn't do it every day.
Let's go to macro scale: What's the better solution: 1000000 people each baking their own bread (1 loaf a day), or a giant company baking all the bread? A million stoves are most certainly less energy efficient than the professional industrial ones at the company. Having to divide the resources into many small packages and distributing them to each individual households is less efficient. The quality of the bread will vary widely. And lets say baking takes 0.5 hours, that's 57 person years wasted per day to do something the bread factory can probably do with a few dozen employees.