I'm in support of you rescuing that dog and dont let anyone tell you different. Its god's animal and when it comes your time at the pearly gates, that's one less question you need answer.
Those who base their decisions on their wallet, will find themselves in a difficult situation when they have little experience deciding matters without their wallet.
No one can determine what future lays ahead for you or that puppy and don't be beaten by pessimistic opinions. Usually those pushing their views live their lives unhappy and sometimes dont even know it.