How is the comment saying anything about the poor? If I got UBI I would instantly quit my well-paid job and just slack off all day long. It has nothing to do with being poor or not.
Why instantly quit? UBI gives you more negotiation leverage because the consequences of being fired are much less severe. You could probably negotiate better working conditions or fewer hours in exchange for less pay.
There's a whole range of possibilities between low pay, maximum freedom (nothing but UBI), and high pay, low freedom (continuing to work as before). That's one big advantage of UBI over other benefits schemes: there are no breakpoints where working makes you worse off.
How many people with substantial inherited wealth just slack off?