The counter to this is that people will be encouraged to contribute to things that do not make them a living like editing Wikipedia, contributing to open source

The counter to this is that people will be encouraged to contribute to things that do not make them a living like editing Wikipedia, contributing to open source software, gardening, politics, volunteering, etc. because they can do whatever they want without getting paid for it. The benefit of basic income is that it does in fact incentivize you to work because you do get more money if you work part time, as opposed to current programs that decrease your benefits quickly as you get more and more hours. But even if we assume people work less with BI, but live happier lives, what is the goal?