The loss of lions has a negative effect on Africa's fragile ecosystems. ... Without lions to control them, these species can out-compete other animals, causing their extinction and reducing biodiversity. Tourism is also a major boost to African economies and lions continue to be the biggest attraction.

Lion threats vary across their range, but the IUCN identifies a few major causes for the decline. For one thing, many of the animals that lions eat are also disappearing due to habitat loss and the growth of agriculture to feed Africa's growing human population.

Threats to Lions. Lions are facing an indirect threat from climate change called co-infection. ... Lions are also facing many human threats such as population growth and agricultural expansion resulting in loss of natural habitat, as well as hunting, poisoning and poaching by livestock ranchers.

To best meet the challenges facing remnant lion populations we should be clear about the causes of their continuing decline and the threats to their survival.  

Loss of habitat and natural prey
Conflict with humans and livestock
Unsustainable trophy hunting and trade in lion parts 
Disease and climate change
Inbreeding Depression

Canned hunting 

Lions are far too precious. And they are not "just" animals. And no they are not a danger to people. Only if given the chance. They are living animals too, and they have hearts and personalities as well. 

THEY DESERVE TO BE SAVED! And not be killed just for their skin and other parts for some kind of illegal form of "medicine"