Unfortunately many of these African countries rely on the money generated by the big game trophy hunters.
Some of it goes back in to preserving game reserves, conservation etc. They say these Lions and other game are in a way superfluous and would probably die anyway. Young mail lions are soon a threat to the pride and are driven away, where they lead a nomadic type of life until they they are powerful enough to form their own pride, most die in battle. I don't claim to really fully understand it but it may help to see things from different angles to get an idea of the bigger picture.