You really don't know much about keeping large snakes, do you? Anyone who has invested the massive amount of time and money it takes to buy, house, raise and care for a large snake, is not going to bat an eye at food costs. That is just silly. Oh, I invested $50,000 for my new Corvette, but oil changes are expensive so I'm just going to let the hick down the block change my oil so I don't need to spend $50 to have it done right. I mean he knows what kind of oil a car like this needs right? The black kind.
There is no logic to your argument. I am sure there are a FEW people out there, who came by their snakes in a round about way and who barely meet the requirements for keeping one alive who might snag the odd rabbit or guinea pig to feed it, but to say the majority of large snake owners do it to save money is ridiculous. Tantamount to saying everyone who owns a cat goes looking for free birds on the internet to feed it. It's silly.
Not to mention that lots of snakes imprint on certain prey items. So why would any owner risk a snake imprinting on a puppy and refusing all other food? How on earth could anyone expect to find a steady source of puppies to feed? That is beyond ridiculous. They main prey items of most snakes, large and small have the distinct advantage of reproducing quickly. Rats, mice, rabbits even the odd quail for certain species, all of these animals reproduce at an alarming rate. Hence their suitability as prey items. Not to mention they are readily available to pretty much everyone.
You can go ahead and stubbornly cling to your idea of giant snake owners snatching up free puppies for snake food. The way I see it, someday they are all going to choke on the spiders who hatch in their stomach from chewing that gum laced with spider eggs.
Gale