Would extra entrepreneurship make up for their loss of production? Maybe, but I don't think entrepreneurship and employment levels in nations where welfare provides everyone with guaranteed "ramen profitability" are encouraging on that front.
Think of it another way, we're getting the above mentioned losses of human production anyways, because vast swathes of human mass will be made completely obsolete. Except without redistribution they won't be playing video games, writing bad poetry, or going rock climbing, they'll simply be starving. The question is do we let them hang, while those lucky enough to inherit server clusters running AI and fleets of self driving cars sit back and solely claim unprecedented concentration of capital?
A very appropriate fear, given that most business ideas are terrible.
There is a balance between risk and reward. Good ideas are worth risk; bad ideas are not.
Removing the fear of failure (or correspondingly, the rewards of success) damages the decision-making process.
Tnere is just as much reason to believe that randomly trying various entrepreneurial efforts would be just as fruitful.
I would think, especially on a site like HN, that people would realize just how valuable BI would be to entrepreneurs. Many people don't pursue business ideas for fear that they'll burn through savings or have problems paying for the necessities of life. With BI, that concern goes away. You may have to scale your lifestyle back a bit, but you basically start at ramen profitability.
And yet all discussions of BI tend to frame it as an extension of welfare given to people who can't earn enough to support themselves. I'm not against taking care of the poor, but when you frame the argument like that, you miss the benefits to society from all that extra entrepreneurship.