It depends on the situation and their expected quality of life. If it will give them another year or two with good quality of life, then I don't see...
I think if an animal has some severe problems and you're throwing money at a vet, you're just doing more damage and making those last couple moments...
A fair fight is a fair fight. What happened to that kid was bullshit and if I were his dad, I'd be looking for some parents to kick the shit out of....