I won't support my taxes going up in order to let people stay home and not work. I wouldn't even pay for that for my own kids, I'm surely not going to do it for some stranger's kids.
There are three cases that are far far more common, i'd guess 2-3 orders of magnitude. First, the person having a bad time. We've all worked with the guy who got cancer, or is going through a bad divorce, who just becomes worthless at work. Not everyone gets that bad, but some people can't keep it together. Those folks just need some time. In a year or two they'll get back on their feet and be amazing productive members of society.
Two, the crazy homeless guy. Part of that is not really being capable of asking for the help they need. I'm not sure what fraction are (i hate to say it this way, but there it is) fixable. I do know that getting drunk, passing out when it's 10 below, and going to the hospital consumes hundreds of thousands of dollars a year.
Third, it's not true of everyone, but there are certainly people that just can't work. Hellen Keller, perhaps some disabled veterans. Maybe someday, but there's no hope today.
A zero tolerance policy might be best. I'd say, we're better off as a civilization recovering as many people as we can, and just suck up the fraud caused by the handful of losers. I don't know how to avoid that, but i agree with you, fuck that guy.
I think the key is picking a bare minimum standard, and any work beyond that is better. People need the incentive. Maybe it's just to buy booze, who cares? Working 5 hours a week must be better than actively avoiding work.
(perhaps not basic income, but that captures the idea of incentive to work while providing a worst-case floor for people. Perhaps the Scandinavian floor is unsustainably high.)
The non-workers still contribute to the economy with rent, food, bills, they're just horribly inefficient. Furthermore, 1 J.K. Rowling offsets a whole lot of people who actively avoid contributing. The possibility to live in poverty and create art has some pretty profound cultural effects.