Hello, I'm not that informed about UBI, but here is my arguement:
Everyone gets some sort of income, but wouldn't companies just subside the income by raising their prices? Also, do you believe capatilism can co-exist with UBI?
At first, maybe. But that's the neat thing about capitalism and the free market: the first to lower their prices again has a huge advantage. There's always an incentive to operate at minimal profit.
Why wouldn't UBI and capitalism be able to coexist? It makes MORE capitalism possible, as it were, expanding its principles of supply and demand to fields such as employment. Right now, people need a job, any job, and if there's no job that fulfills your needs, tough - you take the shitty one and you'll like it. With a UBI, you could shop around for the perfect job, choosing the best offer, or not "buy" at all right now because the market doesn't offer what you want and it's not like you're going to starve without a job. Employers would be forced to make YOU an offer that YOU can accept and if they can't operate under these circumstance, tough. Capitalism in a nutshell, really.