I have, I built a subscription coloring book business when they became a huge fad. It was profitable (between $500 and $1,000 a month in net profit) and I sold it after 10 months when I needed to relocate outside of the country for work so the burden of managing it would no longer be worth it. I also joined somebody else's side hustle in the employee engagement space (tips for managers and a simple tool to keep track of staff info like birthdays, favorite food, etc.) that was acquired by a larger but still very small company in that space. Both "exits" were not in the low 5 digits so nothing notable but a nice feeling