[noarchy]

What you call "BS jobs" are necessary to someone out there right now. That said, if they cannot fill those jobs because UBI is more attractive than the wages for said jobs, indeed one might find those jobs to be automated in the future - ironically (or not?) leading to more "need" for UBI?

[grecy]

In Australia the minimum wage is $19.49/hr and it has the world's most liberal welfare where it's perfectly easy for anyone to get $1130/mo (more if you have kids, more for rent assistance.) even university students can get paid to go to school.

Those things have been true and in place for decades, and they have not destroyed the economy. There are not jobs that are unfilled because people don't want to do them. In fact Australia's economy survived the 2008 crash as well as the best in the world, and continues to be very strong.

You don't need to make guesses about what will happen if free money from the government is available to the masses, you can look at places that are almost doing it already.

[noarchy]

It sounds like wages are higher than the welfare number you quoted, so I wouldn't expect people to necessarily drop out of the workforce en masse.