Should endangered animals be saved? Every single species has a potential for extinction and millions of species have already gone extinct without any interference from humans. Humans have also been the direct cause of several extinctions including dodo birds, Tasmanian tigers, and passenger pigeons. Was it wrong? Of course it was, but could we have saved them? Probably not.
Currently polar bears are in real danger of extinction due to human actions. Thousands are starving to death every year and the numbers a declining at such a rate that humans likely will not be able to stop it. But should we make heroic efforts to save them, maybe not. Without their natural habitat, polar bears will need to be artificially supported throughout their individual lives. This means either the bears end up in zoos(much like what has happened to pandas) or we would have to track each bear and make sure that each one is getting enough to eat every day of their lives. And, someone would have to be responsible for killing seals to feed to polar bears.
Polar bears are declining because they are not able to adapt to their changing environment quickly enough. If we can stop polar melting they would have a chance but if we can't do that then it is better to let the species pass into history than it is to put them all in zoos eating horse meat for the rest of their lives.
The same is true for all endangered species. If we can't fix the main problem that is causing the extinction then it makes no sense to preserve a species by dooming that species to live in an unnatural state.
Would you keep the last passenger pigeon in a cage to preserve it from extinction or let it fly free for it last remaining days?