This assumes that people on a UBI just chill at home and play video games the entire day, which was disproven in about every experiment that was ever run on this.

It’s human to want to contribute to society; and people use UBI mostly to get their shit in order, and THEN to get a 2nd degree and rejoin the labor force.

So, yes, they would in fact become teachers, nurses or or constructors.

Weird it was disproven because that's exactly what I'd do, and what many people who retired early, or in their young 60s, do.