The idea behind universal income is to take care of people who can't afford the most basic of needs. That sounds great.
But why then should the income be universal when the situation where somebody cannot afford basic needs is not a universal situation?
For example, in the USA, anybody making over 50.000 dollars should certainly not be struggling to make ends meet. We are probably talking at least half of the labor force. Why should they also receive a basic income?
It just seems to make more sense to give a basic income to people that are already struggling, with an income below or at least near some sort of poverty line. The whole problem with UBI is financing it, and financing it would be a lot easier if we weren't wasting money giving 1000 dollars a month to a guy already making 6 figures....
Another argument is that incentives are not distorted. People who don't receive the basic income will obviously not have any change in their incentives*, and people who do receive the basic income are poor to begin with, so obviously their incentives are less relevant, since they aren't major contributors to the economy anyways.
*not quite true that people who don't receive the basic income won't have distorted incentives. If you are only just ineligible for the basic income so that you would be better off working less and thus getting the basic income, that would be a problem ... but it's easily solvable: just make the payment of basic income linear so that those "discontinuities" are dealt with.