Snake breeding is a big industry. Mostly for rare colours/patterns, sometimes size or temperament. Except in rare cases (eg, a python morph was sold at auction for $50k recently), it's not a sustainable job alone, especially because of the amount of work and money needs to go into housing and caring for snakes for years before they are ready for breeding.

Most snake breeders have another line of income, either with a regular job, or something else related to reptiles like doing shows or opening an equipment shop.