One key to thinking about how the Plan [improves quality 
  of life] is the universality of the grant. What matters is 
  not just that a lone individual has $10,000 a year, but 
  that everyone has $10,000 a year and everyone knows that 
  everyone else has that resource. - Charles Murray

This is the most important part of any UBI scheme. It's the "U" part - universality. Life is so much less stressful when the need for competition is removed from those who don't desire to compete.

Case in point, you'll be much less likely to be shot and killed for the contents of your wallet when both you and the mugger start from an equal footing. It's the mismatch between the mugger's means and his expectation of yours that motivates his malicious intent. When everyone gets a UBI, you straighten the Lorenz curve, and everyone gets closer to equality.