A Pro Box Promotions matchmaker and son of Garry Jonas divulges their business model (4:05:05). Subscription revenue (no ads), ad-supported (YouTube, etc.), ticket sales (capacity of ~800). They have no interest in championship boxing, which is why their events are during the middle of the week.
Source: youtube.com
https://www.youtube.com/live/ySzeJt6NYnk?feature=shared&t=14750