It goes without saying that puppy farmers are despicable human beings. However the reason why they are able to unscrupulously breed and sell puppies for such horrific amounts of money is because there are people out there who are willing to pay their prices.And the more they pay, the more dogs they will breed, and so the cycle continues.
There have been plenty of articles recently of puppy prices more than doubling over lockdown even from so-called reputable breeders...
Yesterday I was talking to my sister about what to get my mum for Christmas,and as a joke I said that my dad should get her a puppy,and I found a link to one of the breeds we had as kids on petsforhomes.They were £3500. 
Now I will add here that there was never any actual intention to buy a puppy, but clearly someone will buy those puppies,and someone will make a fortune from selling them.
So, if you’re paying £2500/3000/3500 for a puppy then you are part of the reason why the puppy farming trade exists.