What is the fine-grained topic of the following text: Butch Vallotton like most knifemakers started making knives as a hobby, had to start selling knives to pay for his hobby and before he was aware of it became a professional full time knifemaker in 1984 with a waiting list of customers at the age of thirty. Only return the topic.
Butch Vallotton's career as a professional knifemaker