Stitch grew up in a rough neighborhood. He got mixed up with the wrong crowd, and when his best friend took a knife to the chest, he knew the gangster life wasn’t for him.
 
He applied the skills he learned during his relatively brief stay with a local gang to a new, slightly less dangerous line of work - being a bodyguard. He was damn good at it - not quite the most imposing figure, but more than tough enough to stand his ground. But still, this work just didn’t suit him. He didn’t have it in him to get rough with anypony that he needed to get rough with, and when he took a knife to the chest, he decided to quit.
 
He tried a lot of stuff after that, but only one thing stuck with him. 
Making clothes.
 
He turned to an honest life of fixing up old clothes and selling them at a price slightly higher than what he bought them for. Not the most lucrative business, but nopony needed to get hurt, and he found it soothing. Eventually, he went on to start making his own clothes. He never wore them (he has an old business suit and tie from his father, what other clothes could he need?), and he had even less reason to wear them when his focus shifted towards making dresses.
 
He takes pride in his work, and while the clothes he makes are nowhere near ‘top of the line’, they’re not only affordable, but they’re also rugged, comfortable, and are simple enough to look good with just about anything. ‘Practical Fashion’, he calls it. Maybe some day he’ll get the attention of someone with lots of money and interest in his work.