
As you can see from the replies to breed dogs ethically it requires a lot of money time and effort. Because of the responsibilities for the puppies produced for the rest of their lives, ongoing back up for new owners, it is next to impossible to make money out of breeding dogs properly.
The most that a breeder worthy of the name can hope for is to recoup a little of what it costs to maintain their dogs. Some people supplement their Hobby breeding dogs by running a business to do with dogs such as boarding or Pet Supplies, but will not be gaining real income from the dogs themselves after expenses.
Just as an example. I own a medium size breed that doesn't eat a lot. My oldest bitch now 12 had two litters which in theory made me a profit of £800 (she had two litters of four pups), now you can do your sums, but she has cost an awful lot more than that in her 12 years of life.
Her daughter did rather better and had 3 litters, on one I lost money, and on the other two I made a reasonable amount about £2000 in total, she is now 9 years old, and hopefully will live around another 4 or 6 years. I have just spent £400 at the Vet to have a small tumour treated, and she has mostly been healthy through her life, except for a tail injury last year costing £200.
Now the dogs I feed at bulk costs at 30p a day, that is £110 a year for a dog that eats only 8oz of food a day, then innoculations, worming and flea treatment will add a further £65 and Insurance (or money set aside for vet) £150 means each of my dogs costs me £325 a year, without including any treats, bedding, equipment, show expenses, or boarding costs if I go away.
Multiply just that cost by the average 12 years is well over £4000, so as you can see my two oldest ones have been very poor business,and I expect the same for the others.
Now Giant breeds will eat huge amounts, cost a lot more in Vets expense, and tend to be more prone to certain health issues. They do have larger litters and shorter lifespans, but it is swings and roundabouts.
The only people that make money from breeding dogs are those with no scruples, who scrimp on basic care, overbreed their bitches, and dump them at the end of their productive lives, that is why decent dog breeders despise them.
The products of their business are sold to anyone who has the money, regardless of suitability, and they do not take an interest in the pups or their owners after the sale, and breed devotees and general rescue pick up the resulting pieces.