We looked at this in my economics module at uni and I actually think it makes sense. There’s no other benefits paid on top so it’s a simple case of if you have an NI number, you get the UBI. It’s paid for using the administrative savings of calculating and managing the other benefits and you don’t get a personal tax allowance so has some simplifications for HMRC. It’s calculated to allow people to live simply and then if they want a better lifestyle, they need to work to top it up. It could also be introduced hand in hand with things like a 4 day working week, which could stimulate the tertiary sector thanks to increased leisure time and lead to fewer mental health problems which are a drain on the economy.
I also think it will benefit pensioners, particularly those that don’t get the full pension as they should have enough to live comfortably on. And it means people could potentially retire earlier, which opens positions in the workforce.
Also, because people have something to fall back on, it could encourage more entrepreneurs, writers, artists etc!