UBI is needed because most of the jobs people are currently doing are already not needed. They are needed just to redistribute wealth, but most of the jobs are currently already useless (if you work in corporate, public sector or retail you know what I am talking about). In the future more will become useless. Current copyright laws are already outdated and don't work anymore. Only safe solution for people who want to dedicate their lives to visual art is UBI. Because of the known reasons. Most "artists" are not really doing art, simply a job for entertainment industry that in the future will be done by much fewer people due to technological and organizational changes. As it is already happening now, even before AI.

UBI is a solution for similar situations, that will be even more common in future. We need better solutions to redistribute wealth, from what you call "power brokers" to larger society