People still work in countries with free medical care and education.

I think the effect on motivation is the central issue of UBI. There might need to be an adjustment. I know for myself, it can be helpful to be compelled to do something that I've been putting off. Sometimes, people don't feel they have a reason to act, but having to go to work can help. It prevents inactivity and isolation.

Perhaps a focus on mental health and intrinsic motivation will be the answer.

But I think most will naturally aim at higher goals than survival... as they do now.