'Survival of the fittest' became largely irrelevant in humans once we became capable of passing complex information between individuals and generations. Survival of the fittest still exists, but it's not in the individual organism but rather in the ideas, societal structure, and technological innovations that we devise that helps improve us as a species. For reading on this topic you might as well go to the source and read 'The Selfish Gene' by Richard Dawkins.
The argument that we'd all be better off if we were forced to compete in some grand primitive indirect battle to the death is a really tired one. I'm not sure why people cling to it so much, maybe it's because they think they would come out on top. But truthfully, I'm happy that we've (mostly) left this part of our history and progressed to longer life spans and comfortable lifestyles. It's easy to sit in your comfortable chair and type on your computer that costs more than most people live off of for an entire year and spout nonsense like this. But if you were in some country where you were not so fortunate, and people around you were dying of simple diseases, and you were actually experiencing the process of 'natural selection', you might have a very different opinion.