I expect that advances in AI and robotics will make most human labor obsolete (economically unviable) in the next few decades. I expect widespread adoption of UBI as a consequence.

I have also considered the fact that most people just sort of "drift" if there isn't an external system forcing them to stay on track. I suspect we're going to see "fake jobs" subsidized by the system for the sake of maintaining widespread sanity.

Well fake jobs isn't quite the right name, rather they'd be real jobs but a portion of the UBI budget (or wherever it comes from) would be spent maintaining a human economy for the people (most people?) who apparently require such a system to stay sane. I say fake because they wouldn't be economically viable without the subsidy.