I wish a different adjective was used other than 'stupid', because it can distract from the point of the article (I wanted to come up with an acronym - best attempt: Someone Too Unsuitably Positioned In D workforce, and finally asked chat gpt: Someone Tragically Unqualified, Poorly Integrated & Deployed). Anyhow, I don't take it as an insult to anyone, but simply people's circumstances (limited opportunities, lack of education..) can make it difficult for them to positively contribute to the system.

So by "working", the author really means "working for a wage"?

its not so obvious that the stupid person won't provide positive returns at the margins.

i'm sure there are a few people like that and they should be in disability or other government programs. but vast majority do provide value and should be working.