I have a purebreed, bought from an ethical, well researched breeder. I checked and cross checked everything (health results, registrations, number of litters bred in a year, number of litters from each bitch, frequency of litters, number of dogs owned. You name it, I checked it). I went to visit the breeder before the mating had even happened, to look at their set up, go through all their paperwork and meet the bitch and their other dogs (4 generations of breeding and ex breeding bitches). I then went again once the bitch was pregnant (4 months later). I know my dog came from ethically bred stock and a loving environment that cares about welfare.
As for the money side of things, breeding ethically and healthily is NOT cheap, no one in their right mind would do it for free! Health tests (some of which have to be done annually), equipment (whelping beds, heat lamps/pads etc), insemination or stud fees for health checked sire, fertility tests for the bitch to check she’s ‘ready’, scan fees to confirm pregnancy, potential vet fees for any pregnancy care or problematic, vet fees for puppies (regular flea & wormings, health check, microchipping, vaccination), KC registration. Plus probably loads of other incidentals I don’t realise.
It isn’t a guaranteed goldmine either, you could be a big litter and make a small profit but next time you might have a single puppy or two and make a loss. Unless you are doing it like puppy farmers, large volumes of puppies bred without veterinary care or health testing, I doubt anyone is retiring to the Caymans on the profits.