South Africa is already the second largest economy on the continent, and accounts for 24% of the continents GDP. Trophy hunting accounts for a fraction of that tourism contributed to South Africas GDP in 2013. About 8,500 trophy hunters visit South Africa each year, compared to around 9.5 million tourists.
A resource economist who worked across Southern Africa and established a national environmental economics program in Namibia, Dr Jon Barnes, wrote in a 2001 paper: Consumptive wildlife uses [such as hunting] are relatively unimportant in terms of economic contribution..."
That being said, the theory that money from trophy hunting goes directly into communities and conservation is questionable at best. Research published by the pro-hunting International Council for Game and Wildlife Conservation and the U.N. Food and Agriculture Organization found that that hunting companies contribute only 3 percent of their revenue to communities living in hunting areas. And according to a 2013 report by the International Fund for Animal Welfare, trophy hunting accounts for 0.27 percent or less of the GDP of each African country in which its conducted.
(Why Are We Still Hunting Lions?" National Geographic Magazine)
"There will be consequences as well as benefits." Fewer lion deaths, your allegations notwithstanding...