I think most importantly, it would give us the leverage to say “no”. To walk away from bad jobs and abusive managers. To refuse to work in unsafe environments. To demand better pay.
To demand better, because the options are no longer “suck it up” or “die”.
The counter-argument: Not having UBI is in the interests of those in power who want to do anything to the people they are in power over in order to remain in power.
If the greed of the few should come before the need of the many.