Go to a mental institute if we tie the UBI to some basic factors. UBI isn't just some altruistic factor that gives money to everyone without condition. They at least want to make sure you're a citizen and not going to fund the destruction of society with it.
>if we give people some amount of money for nothing, they'll magically pick up art and entrepreneurship and other productive outlets spontaneously.
Talking about non-homeless, it has shown to increase recreation. Not necessarily businesses, but it's nice having time to breathe when you aren't spending half your like just to make sure you can pay rent.
>What's going to happen, if we're foolish enough to try UBI,
You can speculate or you can actually read studies done. Domestically and worldwide.