There are professional bakers that use cake mix. Cake mix is basically the exact same ingredients as one would use if making their own, sometimes with the addition of ingredients that are usually improvements but that almost no home baker would regularly carry. Among all the various pre-packaged/pre-prepared ingredients, dry cake mix is probably the one for which pretentiousness about quality makes the least sense. And this comes from someone who never uses them and makes 100% of my own cake batter....but that's because my family bakes enough that I always have all the of the necessary ingredients on hand, so there is almost no extra convenience for us.