As for benefits, likely for everyone. People don't work just to make money, people make money since they work and produce for society right? Making money was never the end goal, and if we can avoid more work, that should be better for society as a whole.
In short, automation shifted the amount that needed to be done in certain industries. AI could possibly make shift so large that there won't be enough work for everyone to do.
I’m really not trying to argue for or against any new technology. But I don’t see why any new technological change necessarily brings about UBI given the absolutely drastic reduction in the amount of labor necessary for human survival we already achieved in the mid 1900’s. So my question is still, why did the old forms of automation not bring about a post scarcity utopia (or at least a UBI)?
I wasn't trying to say that people don't work for money fullstop, but rather that money isn't what people are trying to get ultimately. People want things, things that make people happy and alive. They get money in order to acquire those things.