This assumes people just stop doing anything of value if there no longer is a proverbial stick in the form of financial ruin if they stop working.
Nobody is saying that the carrot (personal financial gain) needs to be removed from the equation. Just that everyone is guaranteed some basic level of financial support.
Society already produces enough wealth to cover the expense of UBI. Remember it would replace any other welfare systems in place today.
Personally I think I might take a bit more risk, and choose to do something that I personally believe is of actual value to society rather than please some corporation or VC.
