I'm going to assume by "pay a person enough" you mean pay a living wage. But now we're back to one of the key criticisms of UBI - reduced labor supply leads to

I'm going to assume by "pay a person enough" you mean pay a living wage. But now we're back to one of the key criticisms of UBI - reduced labor supply leads to higher wages but reduced employment, increased prices, reduced economic activity and consequently decreased consumer surplus (which would be a bad thing).