People who arrive invited, with passport and good reason/qualifications to make better life in any country are normally welcomed in.
Invasion of illegals arriving through the back door is a massive problem almost everywhere. One point to sleep on at night you know your people, country and are a citizen, making a future for oneself is a problem when man made law is imposed.
South Africa has never been the land of milk and honey we have lived under draconian rules for a very long time, first the NAT then ANC parties, perhaps now that is at a long stretch still, under GNU some level thinking may enter.
I don't know a lot about the history of South Africa, but I grew up having a lot of friends from SA who I connected with on Facebook. Some of them even wanted me to come to South Africa as well. So I had many friends.
It's true that some people have misused their opportunities and done terrible things, but majority of people or some people actually just want to leave their country to see a fairer place to establish themselves
Each country comes with unique problems, many move never satisfied in country of birth for variety of reasons.
Those who invade, or arrive to do wrong by those who reside in a country would do the same in their own homeland.
Worldwide movement with easy travel and technology has happened, it's in resolving problems amicably.