I run a shop in which we sell handmade goods of all kinds. Emphasis on "hand" - sewing machines don't agree with us! I've made a fair amount of skirts, a couple dresses, a couple Renaissance wench outfits and even a fella's shirt and pants, and I have also made myself a couple massive shawls which I wear to keep warm at the office. I do knit far more than I sew, to be honest.
I don't have time to make my own clothes. Also, good quality material in a fabric store can be expensive. When you add the cost of your time with the cost of materials, it can cost more money to make your clothes.