I think the operating word is "some," not all. We know that UBI will sometimes be misspent. Most if not all aid programs have this problem. That doesn't mean it isn't worth it for those who would put the money to good use.
It's a problem if the math behind UBI presumes savings from eliminating a ton of social programs and we later find that there are substantial numbers of people that still need those programs even with UBI for non-financial reasons.
If we find that non-trivial numbers of parents blow all their UBI on XYZ, are we really going to let their kids starve? Or will we see that programs like SNAP need to remain in existence?
I think a good UBI program will eliminate the crappy social programs, and will keep some around to help transition people to the new society and also to help people who aren't helped just by having money to spend. For instance, child abuse: we have CPS for a reason, but giving everyone a monthly check isn't going to magically eliminate child abuse, so obviously we still need CPS for that. There's plenty of other places where we'll still need social workers to help people. But the savings we'll realize by not having armies of government workers making sure someone isn't "cheating" by getting a welfare check and then trying to supplement that with another source of income, along with various other benefits, will help pay for UBI. And eventually, by eliminating poverty and changing the culture (with both UBI and social workers), we won't need so many social workers.
Is over-hiring of social workers in welfare sector a problem in this country? It seems that applications for something like SNAP are handled online, distributions are done directly to debit cards, and a bunch of enforcement and fraud prevention work is offloaded to agencies like SSA and IRS.
I don't have any numbers handy, however I think it should be fairly obvious that even with some stuff handled online, there's still a lot of federal workers behind the scenes. Anyone who's worked in the federal government knows there's a ton of federal workers who really don't do much all day long, and get paid a lot for it.
If the SSA and IRS don't have to do so much enforcement work for entitlements, that's a bunch of people there who can be laid off to save taxpayer money.
For SNAP they did the analysis of various policy steps that could result in administrative savings - https://www.cbo.gov/sites/default/files/cbofiles/images/pubs... (it's a very wide image, so zoom in and scroll to the right until you hit "Policy Options").
Eliminating the asset test (the area where undoubtedly some government employees work full-time) would actually increase the program cost. Most of the savings are actually derived from juggling the numbers behind "the cost of a nutritious diet".
I am personally not opposed to going full-throttle on something like SNAP - just send a free card to anyone with a SSN who requests one (I am sure agricultural and retail lobby would concur), but I think the potential savings are overblown - Medicare, SS and SNAP are generally tightly administered.
If we find that non-trivial numbers of parents blow all their UBI on XYZ, are we really going to let their kids starve? Or will we see that programs like SNAP need to remain in existence?