With UBI, it’s challenging to find a proper balance so that it helps people, rather than hurt them. While the ideas behind it are virtuous, it would be impossible for it to replace welfare programs completely.
The perfect amount to give people in place of welfare is a number continually changing to fit with the current economic stability along with a person's state of affairs, such as family and medical problems.
It’s hard to predict these numbers, making it that much harder to implement. Even if there were an agreeable figure, it's not feasible to believe it could function at capacity. To completely replace welfare state will not save the government money but drain it.
It’s not even extenuating circumstances that are the problem in this situation but people themselves. Not everyone is good with money, nor do they know how to save properly. Coming into extra money does not always mean they are taking the initiative to have a safety net in place. Human beings are terrible at long term planning. For too many, extra money means having more to spend, not save.