It seems to me that the problem many retiring people run into is that they have been compelled to labor for the entire life by economic necessity and so viewed retirement as an escape into self-fulfillment, without ever having time to consider what self-fulfillment means, and first really are able to even consider the question in their senior years, burdened by mental habits of decades of servile labor.

In a system where people don't usually feel an economic compulsion to work if they are at all able (which is probably not a UBI at the poverty-support level usually suggested as a near-term goal, though that might have a shadow of the same effect) you'd have a lot fewer people running into that problem; they'd learn and organize their life around it when they were much younger.

No need to infantilize the retirement-age elderly -- the ones that want to work can still work, and they'll do so in a better job market with less power asymmetry between employers and employees.