"The author isn't attempting to say that capitalism is forever and UBI won't work because capitalism is a natural law. She is saying that capitalism does not work, and we can't simply 'patch' it with UBI to make it keep working like it used to. It's a broken model, and the groups latching on to UBI as a kind of panacea for the many problems that emerge from it are barking up the wrong tree, because it'll maybe tide things over for a few decades before the fundamental contradictions cause it to collapse again."
But then that evokes a paraphrase. "Capitalism is the worst system out there...except for everything else." Meaning that if the best option we have for society is hopelessly broken, we're basically sunk. You say people are essentially needy. I say people are needy AND fighting with the neighbors. Many say economics isn't necessarily a zero-sum game. I saw it DOES at time, and it at THOSE times when things get ugly. When there's no external crisis or issue (like a war) to force us together, we start to turn inward and compete with the neighbors. It's instinct: humans I feel are most fundamentally social only in a tribal sense. We form immediate attachments to family and perhaps one level up, but when it comes to the neighbors we tend to be more mercurial.
Anyway, the discussion leads to what I feel is a fundamental human trait: humans will cheat if they can get away with it. And that affect any and all economic systems humans can devise. Some human somewhere WILL (not MAY) find a way to game the system...ANY system. And since it's practically instinctive in the human condition, I don't think it's possible to fix it (because there are those who have the will AND the means to actively prevent it because they benefit from it) without creating a better human, and as the saying goes, "Nice guys finish last."