The poverty rate is just under 50%, per Wikipedia at least. If all the money is coming from the county (presumably it is), then it's going to be coming from the other 50%, and at a rate higher than neighboring (non-UBI) counties.
It will be in the rational self-interest of that non-impoverished 50% to leave. Labor will be more expensive as fewer people want to do less-desirable work due to no strong need. I don't know how freely workers can move between counties, but obviously I imagine some people in neighboring counties will want to move in for the free paycheck.
Over time, you've chased out the productive people and bolstered the less productive ones, and you're drawing from a smaller and smaller pool to pay for a larger and larger group of people.
I've always felt like UBI is unsustainable, but at least worth debating. I haven't yet seen even proposed what should be done if UBI fails this way, though.
I also don't see anything about people moving in or out.
Put plainly: It's not surprising at all that one can take a lot of voluntarily-given money and distribute it to an impoverished village in Africa, resulting in them being happy and saying they're seeking work (in the short term). Normally, though, that's called "charity" rather than a UBI experiment, and even UBI opponents will acknowledge the likelihood of that happening.
Isn't assuming this the basic failing of economics as a science? Not trying to be provocative, sincerely asking.
When the federal government started subsidizing higher ed loans, it is not some unimaginable outcome that higher ed prices will increase. Banks, colleges, students, and parents are all operating in their own self-interest, but by artificially making more money available to consumers, they are naturally willing to spend more.
It's just a sign of really bad policy when nobody is cheating the system and everyone is following the rules, but it results in really bad outcomes. And it's even worse when that happens and blame is passed to those rational actors (banks, colleges, etc.) because that further justifies bad policy.
I believe most of the money comes from outside the country, I started donating $25 a month to GiveDirectly this summer.
In the years to come technology is going to replace the need for a lot of human labor and UBI will be required to maintain a civil society.
So I'm not seeing why you think skills will atrophy? It seems like there's more danger of that when people are poorer? (For one thing, education becomes less affordable.)