Also, another point that this "experiment" doesn't really generalize beyond charity, is that the population of people who get the money, are not the ones supporting the program. The funding for doing this comes from outside donors. Thus, the people who receive money, have no downside of using that money to increase their earning potential.

However, if it were implemented at the government level, people who used their money to increase their earning potential would have to pay increased taxes to support the UBI. The cost/benefit to extra earning changes if you keeping all your extra money, or a significant portion is going towards funding UBI. Once you do that, you may see a lot more people decide that the extra effort is not worth it.

So, this is a great experiment in directly providing money as charity. It does not really address UBI as would be implemented by governments.