"Large rodents" is a broad term, but several factors contribute to large rodent extinctions:
Habitat loss and fragmentation: Deforestation, agriculture, urbanization, and climate change destroy habitats.
Predation: Introduced predators and human hunting reduce populations.
Disease: Introduced diseases can devastate rodents with no immunity.
Competition: Invasive species compete for food and resources.
Natural events: Volcanic eruptions and wildfires may also contribute.
Extinction usually results from a combination of these factors rather than a single cause.