Crni, you keep assuming that a social darwinist wants people to be equally successfull.
In that kind of philosophy is inherent the notion that people are NOT equal, and point to the reality that people, well, are inequal. There are rich people, there are poor people, there's strong people, and weak people.
"weak" in particular, is a very loaded concept, it can be illness or poverty or any other negative attribute
The social darwinist does not necesarily see this as any kind of unfair, beyond the notion that the weak steal resources meant for the strong (yet they seem to disregard that this would make the strong less strong, if the strong are dominated in this way by the weak)
I keep coming back to projecting, because why would someone genuinely strong have such disdain for the weak? In both apes and early hominids, we see evidence of loyalty within a group. Healing remedies are invented by hominids precisely to save the weak from perishing, if they are indeed part of our community. Both physical wounds as well as mental illnesses have been tended to for litterally millions of years in the human lineage, as it can be observed in the fossil record in for example Homo erectus, but also in living chimpanzees (where it has been observed sympathy shown by strong chimps towards mentally ill or straggling individuals, as long as they are part of the same community)
Chimpanzee-like hominids separate from our direct lineage by about five million years, so by "phylogenetic bracketing" we can assume that this kind of attention has existed in practically all branches of hominid for the past 5 million years at least. This makes the idea of "humanism" extremely relevant to... being human.
These boooring technicalities of sciiience and mooonkeys are obviously totally irrelevant to someone with a dedicated fascist agenda, unless they FIT their agenda, like when they adore to bring up how wolves survive due to blood-guzzling viciousness, while completely ignoring that big part of wolf interaction is soft and intimate - that animals communicate ALL ranges of emotion, not only tyrannical and brutal ones
But yeah, in the end, trying to cater to the "soft-hearted humanist" in a social darwinist is a waste of time.