Will they? As a UBI proponent the most common anti argument is that people only work because they have to and if they didn’t have to they wouldn’t. I think that’s pretty true and that most people won’t strive for better if they have their basic needs met.
I think we’re heading to an economy that needs way less workers than we have and UBI will help with the transition and so the people who pull themselves out on UBI are a good thing for the rest of us.