Why work? The amount of money given is not a comfortable life for most folks, a few folks who are super-frugal Clark Howard types would be able to live off the money, but most would want something more, and they would seek jobs. That said, those burger jobs (minimum wage) is gone will have to pay a wage that people are willing to spend their time working, whatever that is- the market would decide from a position of equilibrium.
Also, most people do wish to work and be productive members of society, most people do not want to be leeches. What you would see is more people try to take creative pursuits or start their own businesses- but that's a good thing.
One potential downside, an increase in money velocity could lead to an increase in inflation as it would increase supply of money. This can be controlled fairly easily through monetary policy. Another potential risk is folks who squander their money and starve, but such folks would honestly be mentally incompetent in my eyes, and should be placed somewhere (most likely they'd be drug addicts or compulsive gamblers)
Two other points (you made a lot of points worth responding to!).
One: "those burger jobs will have to pay a wage that people are willing to spend their time"... Congratulations. You just made a McDonald's hamburger cost $19. Again, the only people getting hurt are poor and lower middle class people (the larger portion of McDonald's customers).
Two: "Another potential risk is folks who squander their money and starve, but such folks would honestly be mentally incompetent.." except they wouldn't be considered such at all. They'd be placed on a special government program for people who blah blah blah (read: more welfare and more spending). They'd also get Medicaid, so there's that additional cost you forgot about above.
Come to think of it... how do all of these freebie people who don't actually want to work under your plan get healthcare? Some new government healthcare program perhaps? Or we expand the medicaid rolls? Or we increase the program payout to cover purchasing their own healthcare? Good times.
The larger point is that this is exactly the sort of problem I've been talking about in this thread. We continually pass these magic bullet programs where no one takes the time (whether purposefully or accidentally) to truly understand what the consequences of the program will be for society as a whole. And then we end up in a situation where our magic bullet caused a whole host of new problems, so we need a new magic bullet.
Instead, let's take the time to assess the system honestly, rebuild the flawed parts (hello, tax code, Medicare/Medicaid and Social Security I'm looking at you) and then go from there. Notice I said rebuild, not scrap. But we can't fix them, because even having a real conversation about them in this country is racist or a war on old people or women or the poor or some other bullshit.
Capitalism works (my evidence: the difference in the rate of improvement of human quality of life in the last 200 years vs. all of human history before that). The problem is we have these schemes to solve problems that have pushed the system out of whack so it's no longer running properly. It's possible to find the right balance between social safety net and pure-capitalism. The problem right now is we don't have either, really, and so we have none of the economic prosperity we should have under "evil capitalism" and we have a system that actually functions in a way that hurts the poor and lower middle class and decreases economic mobility thereby hurting our efforts to build a proper social safety net.