I agree with you completely that it's a problem when society as a whole doesn't have a good idea of what it means to be "productive" but I think that in your se

I agree with you completely that it's a problem when society as a whole doesn't have a good idea of what it means to be "productive" but I think that in your second sentence, you could just as easily replace "UBI" with "wages" and the truthfulness of it doesn't change at all. I think working for wages doesn't allow most people to do what I would consider "cultivating themselves," and possessing "marketable" skills is not the same thing as possessing useful skills. Obviously we all have our own definitions of "productive" (I actually like to think of it more as useful rather than profitable) but my own personal opinion is that what is useful and what people get paid for have as little overlap as they've ever had, so the risk of replacing certain jobs with UBI isn't actually as much of a threat to productivity as it might seem like.