The biggest reason I support UBI (Universal Basic Income) has nothing to do with our possible automated future, as labor becomes less essential, or at least as we need much less of it, though that's a great reason to support it. It's not even about eliminating poverty or making the unemployment rate a non-issue, though those are very good reasons too.
The reason I want a UBI is to make work at least -technically- optional. I want this because so long as work is not optional, so long as it is mandatory, it is coercive. I want UBI so that every low wage worker whose boss screws them on hours, who reprimands them for taking sick days, who asks them to work too fast in unsafe conditions (see the current fast-food lawsuit), every young employee whose boss secretly grabs their ass while no one is looking, who's constantly making lewd comments, or racist comments, or any other sort of hateful bullshit... So that every employee who finds themselves trapped in the fiefdom of some petty little tyrant of a boss, which is actually The Majority Of Low End Workers, so that they can say:
"TAKE THIS JOB AND SHOVE IT"
So that they can really, truly, meaningfully walk the fuck away. And not have it mean they end up on the streets or their kids starve or they find themselves turning tricks to keep the water running and the lights on. Or for that matter just ending up in yet another job with a slightly different petty tyrant. And they can do this, deal with this, without having to deal with lawyers or Union Reps, who though are better than -not- having them it'd be nicer to just be able to do it ourselves. Because if -enough- of them (us) say 'NO' to this petty fucking bullshit, then firms will be forced to stop letting the petty bullshit happen (those who fail to will simply not get workers), and work in general will end up less awful for everyone.
Because the ability to say 'NO' to someone who's actively abusing you... that should be pretty high on the list of 'Liberties' worth defending. In my mind.
Almost as important is what a mentor at Pan Am called "Fuck You Money" that puts you in a position to as he put it "To do your job right." If you are dependent on your job for your day to day lifestyle, you can't afford to disagree meaningfully with your bosses to do what is right instead of what is expedient. UBI gives you the safety net, along with your Fuck You money you saved from your productive work to get the next job to use your skills properly.
The economic argument for a UBI is that it is "outside" money to low income people who spend locally for necessities provided by mainly other low income people. The bodega proprietor, (there would be food trucks on every corner) and other neighborhood business would thrive and economic benefits would trickle UP to landlords, food truck lessors, food truck builders, etc. They might even buy a solar food truck with a Powerwall 2 from Tesla if they are really successful.
Entry level jobs, and indeed all jobs would be supplemental to UBI and under conventional income tax theory would be taxed progressively. The big difference would be that entry level jobs would be optional so wages and working conditions must be attractive enough that people would want to work. Most people would rather be productive, whether as an artisan, an entrepeneur, or as a service worker as long as they feel that they are being useful to their community.