You can’t just move assets of that scale around without knock-on effects.

If it was just cash - then payments of that scale would definitely be inflationary. People with debts would gain, lenders would lose, you’d create a bunch of instability in the money markets, and I don’t like to predict the long term effects. In real terms you’re probably going to hurt more people than you’d help.

If you’re imagining a scenario where that level of largess is backed up by huge gains in the real economy, then yes the people receiving it would be better off. But where would that productivity come from? In this scenario the people who sell stuff that the UBI recipients would be buying would be far more wealthy. You wouldn’t close the wealth gap, you’d cleave it apart like the sky and the land.