I invite you to walk the streets of downtown Detroit or, as thehardsphere points out, parts of Appalachia if you still have doubts.
The only reason such areas in the US don't make international news is that third-world countries still have it relatively worse and, even then, governments of other nations issue formal cautions to their citizens against travelling to these areas.
I protest this unseemly slander; I'll have you know that I treat women with respect. /s
In answer to your question, A) you can pretty much find a study that says anything you want and B) a considerable number of my high school classmates from lower and lower middle class families did, in fact, fall prey to drug addiction and I know all too well that, had circumstances been just slightly different, I might have joined them. Am I weak? Perhaps, perhaps. But no more so than a great many others.
Seriously, go to Detroit or one of these other afflicted areas and walk around. Many of these people are already on public assistance programs. If you survive the experience, come back and see if you can manage to still say to me with a straight face that people will find their own productive purpose in life given UBI.
> It's quite a mystery as to why well-educated people persist in the mistaken belief that UBI will magically cause recipients to behave nobly.
I find the reverse to be the mystery - why some people persist in the belief that people on UBI will mostly turn to spending their days abusing drugs and cheap entertainment? Like if humans were zombies who need an employer to give their life a direction?