Do you mean 'unfit' in the evolutionary sense, i.e., genetically?
We in civilized Europe and America have provided a safety net of welfare for these people, but what do you do when the economy contracts and these people keep breeding?
If you say that these people "breed", then you must mean that they are a genetic or evolutionary variant of man, different from the rest. I.e., they are paupers genetically, and pass down their pauperism genetically. This is much like R.A. Fisher, who argued that upperclass British twits and the lower class are two different evolutionary variants of man. Upon reflecting, do you think any of this is true?
I mean “unfit” in the sense of non-adaptability. A “fit” person adapts to changes. Is this a genetic trait? Nature or nurture? I think both, and that the culture of “the group” reinforces tendencies that are already there.
Notwithstanding all the silly movies that have been put out where an aristocrat marries a pauper and creates children that are good-old-just-like-me-and-you Americans, in general, upper-class British twits tend to marry other upper-class British twits. The lower-class people do likewise. Theodore Dalrymple, one of the best authors writing today, tells tales of these people that would curl your hair.
Different evolutionary variants? I can’t say, because, like everybody else on earth, I don’t know the mix of nature and nurture. Obviously, both play a part. But having observed my children’s and grandchildren’s classmates, I know that you can’t put a quart into a one pint container. What do we do with the one pint containers?