Here are a few reasons why:

- Habitat loss: The primary cause of koala extinction is habitat loss. Koalas rely on eucalyptus forests for food and shelter, but these forests are being cleared for agriculture, logging, and urban development.

- Climate change: Climate change is also a major threat to koalas. Rising temperatures and increasingly frequent and severe droughts are causing eucalyptus forests to decline, making it difficult for koalas to find food and water.

- Disease: Koalas are also susceptible to a number of diseases, including chlamydia and the koala retrovirus. These diseases can cause serious health problems and even death.

- Hunting: Koalas were once hunted for their fur, but hunting is now illegal in Australia. However, koalas are still sometimes killed by poachers and feral dogs.

- Car accidents: Koalas are often killed by cars when they cross roads.

Addressing these threats and saving the koala from extinction will require a concerted effort from governments, conservation organizations, and the public.