As a regular reader of mondaynote.com (and so therefore an expert), I have the impression that France has many other obstacles to entrepreneurship. Like their labor laws.
It seems to me that universal basic income, alongside universal health care and other reforms, would greatly reduce the need for stultifying labor laws. More simply, employers could hire and fire as needed.
This is a major disincentive of work.
However, the work that will not be done by those people who can do it but don't want to will still need to be done. The solution will then be to hire people at higher wages.
But since these higher wages are not a result of increased productivity, the employers won't be able to sell more. The result is that prices will go up, generating price inflation. And we know inflation is the worst of all taxes, as it affects the poorest the most.
In the long run, the money received via BI won't be able to sustain the "comfortable living" that it was supposed to.
Sure, above a certain level people's taxes would go up, so they pay back some of their basic income as tax. But that wouldn't kick in until people are earning rather more than $1200 a month.
This also has the inflationary consequences that I mentioned in another comment: you're effectively increasing wages without increasing productivity. This will cause prices to rise because employers will face higher taxes so that the state can support basic income, and demand will rise because people will have more money.
This will cause inflation, and in the long run purchase power will not increase, while society will be worse off with less people doing productive work.
Sure, some people won't work. But most of those would be people who either would have a hard time finding work, or who have some specific other thing they'd rather be doing.
You are also confusing money with wealth. Basic income may give people more of the first, but its inflationary nature does nothing for the second.
Child care? Elder care? Volunteering?
Consider this scenario: you're taking care of you elders and you need to go out and buy some medicine. But the drugstores have all closed, since nobody wants to work there anymore (why would they? They're at home taking care of their elders too). Do you think this is not a realistic scenario in the long run? Why not?