I cannot end my brother's suffering. Only he can do that. The most I can do is offer help, if he'll have it. On that point: Regarding someone as worthless, that is, not only unable to contribute but unable to become able to contribute, strikes me as rather less compassionate than contemptuous. I concede I once thought as you do, but only until, through sheer good fortune, I learned what I could accomplish and, in so doing, earned my own respect -- and found in that the necessary prerequisite to earning the respect of others. Better, I think, to offer my brother the opportunity to do likewise, than simply to presume that he lacks even the hope of ever so doing.
If in a hypothetical conversation, someone said to me "They contribute nothing; they should all just die & starve or just get out of the way." ... my response would be that it's us, the people with wealth(or at least not living paycheck2paycheck) who have the most power to change society and allow it to support them somehow. I don't really know how exactly, but the first experiment I'd vote for is basic-income and see how that pans out.