According to the WWF, 60% of Earth's wildlife has been wiped out in just 50 years, both plants and animals. The leading cause of extinction is loss of habitat due to land clearing - and the vast majority of land is cleared either to graze cattle or to grow feed for farmed animals. As the human appetite for meat increases, ever more species-rich habitats are being cleared.
Citations:
Oregon State University. "Humans' meat consumption pushing Earth's biggest fauna toward extinction." ScienceDaily. ScienceDaily, 6 February 2019. <www.sciencedaily.com/releases/2019/02/190206101055.htm>
Science of The Total Environment, Volume 536, 1 December 2015 "Biodiversity conservation: The key is reducing meat consumption"
<www.sciencedirect.com/science/article/pii/S0048969715303697>