You are right of course, a safari is not that expensive once you have traveled to the place. I myself was 3 weeks ago on a one-day trip from Johannesburg to Pilanesberg. The cost was USD 250 for a trip for two people, with pick-up from hotel, transport, entrance to park, game rides, lunch and drop back to hotel. Anyone who can afford to travel to Johannesburg from Europe, Asia or America can afford that.
The ride around the park is not that bad for nature (it's on roads built around the area, no-go outside vehicles) but if the number of visitors increases a lot, I can see the pressure definitely is a problem (more and more people want to come, so maybe the gate needs to be open for a few more people? And so on.)
I saw many of the impressive big animals there, elephants, giraffes, zebras, GNUs, etc, and to top it all, a leopard waited behind a bend on the road, and walked right next to our jeep so that we could just observe it. It was not bothered by our jeep at all. Even cell phone camera pictures are very good.
It was great to see it. But somehow I felt not comfortable about it. Why's that great animal not afraid of people that drive this ugly jeep right next to her hunting grounds?