As possibly a supporting point, many Americans are unnecessarily on disability(for those outside the US, if you can prove a permanent disability that prohibits you from working, the US government will send you a check every month). They live in low income areas and buy groceries with food stamps. They faked an injury, scammed the system, and now I'm paying for their rent and food. Most people on disability are legitimately disabled, but some are not.
These people are discouraged from working, because, if they are caught working in a manner that is inconsistent with their 'disability', they get in trouble, forfeit their benefits, and possibly jail/prison time for their fraud. But, I see these people routinely trying to work in any way they can get away with. True, some do not, either out of laziness or fear of discovery, but, as a whole, most still try to work.
If that income were replaced with a legal, basic income, I have no doubt more of these people would continue to work and seek work, probably more so since it would not be a risk to their freedom or basic income, and they are the ones currently trying to scam the system. These people are probably at least a subset(or superset) of the demographic that the non-supporters fear most will just leech off the system.
In theory we also would save on the cost of the bureaucracy required to determine who is actually eligible for a particular entitlement. If everyone was getting basic income and we eliminated a bunch of entitlements such as disability and unemployment insurance, then there would be no need for those entire sections of the government payroll.
Of course in order to actually achieve any savings we would need to truly eliminate those other entitlements and fire all of the people that work in the departments that currently oversee them. That is the heavy lift politically.
The same is true for a lot of policies that make sense economically but may not survive contact with the political system. Major tax reform is another obvious example. Everyone knows we could have a variety of different tax systems that are economically better than the one we have today, but in order to get there we need to eliminate some tax carveouts that people love.
The pathway from today to the desired state can't just be hand waved away. If we added universal basic income, what entitlements are we eliminating? How much would that save? What parts of the government are getting shut down, and how much does that save? Who are the winners and losers in the new system?
The government routinely sheds thousands of workers. It's not such a huge change to remove a whole department. It would be cheaper because unlike normal we wouldn't end up rehiring everyone with the domain specific knowledge as contractors.
Some of those people also may have had a disability they recovered from, but no real opportunity to return to the workforce (or no incentive to work towards their recovery). I believe the Social Security office even includes the criteria "could this person get a job?" based on age, skill, and location, and you could remain on disability even though in some theoretical sense you are physically able to work. Such as, you might consider a miner who has some physical reason he is unable to continue in mining; theoretically he might be physically capable of working in some other job, but those jobs don't exist in the community, or he doesn't have the skills and doesn't have enough time left in the workforce to justify retraining.
Which is to say, there are situations where no one is really defrauding the system, but because the rules don't offer any soft landing people have to stay inside a system and can't explore the marginal contributions they are capable of making.
(Still this wouldn't remove the purpose and need for disability insurance, just remove some of the strange structures in it that have developed.)
Maybe I am jaded, living in Santa Cruz, I had a housemate years back on disability and getting money because she couldn't handle scents and some other stuff. She had a handicap placard in her car yet still was able to bike around town for some miles including some slight (50-100') hills. I don't think things are as out of whack as the "Cadillac Welfare Queens" trumpeted up during the years of Reagan, but there are people, maybe only in certain communities, that play up the whole I'm a victim, I'm can't work, you owe me mentality.
Hell, one of the ones locally, managed to get a PhD from the local university some years back but has not had a steady job in over two decades.
The idea of a basic income is interesting, but it would need to be couples with cleaning up some of the able bodied "self proclaimed" victims.
Let's assume for the moment that you're right and there are some people who can work, but chose not to, and use disability as their reason to avoid work, and claim disability benefits.
We can either just give them money, and not care if they label themselves as disabled; or we can make them jump through expensive hoops with complex bureaucracy and end up just giving them the money anyway.
I live in a city and county where I see recent immigrants busting their ass for minimum wage or lesser dollars.
I also see a PhD in CS spending all his time online and playing the victim for some made up disabilities (maybe there is a mental component). I'd like to see a bureaucracy that moves individuals like this into a required work/live support system.
We have a downtown cleaning crew of individuals with Down Syndrome helping out; we have recent immigrants busting their asses in the field, etc. Oh and we also have able bodied, poor mannered, self described disabled white people that refuse to do anything. My favorite was someone I knew through surfing out on "disability" for his back, but he'd still pull into 8-10' waves and was doing ding repair as well.
Personally, I like the idea of a basic wage, but I also know there are people that milk the system and want stop gaps for that too.
Basic Wage means those people aren't "milking the system" - they'll keep doing what they're doing, but it'll cost you less than it costs you now (because you've removed all the expensive bureaucracy between them and the money).
And you're pretty judgemental about mental illness. 20 years ago there was considerable stigma from employers, and less protection in law. Even if he'd wanted to work he would have faced discrimination. That discrimination still exists to some extent, though there are some protections. But now he has learned helplessness. People judging him doesn't seem to be getting him back into work. A programme following the Sainsbury Centre for Mental Health model ("place then train" - get someone a job, then support them and the employer to keep that person in the job) would be better, but those aren't common and they're always over-subscribed.
These people are discouraged from working, because, if they are caught working in a manner that is inconsistent with their 'disability', they get in trouble, forfeit their benefits, and possibly jail/prison time for their fraud. But, I see these people routinely trying to work in any way they can get away with. True, some do not, either out of laziness or fear of discovery, but, as a whole, most still try to work.
If that income were replaced with a legal, basic income, I have no doubt more of these people would continue to work and seek work, probably more so since it would not be a risk to their freedom or basic income, and they are the ones currently trying to scam the system. These people are probably at least a subset(or superset) of the demographic that the non-supporters fear most will just leech off the system.