While of course basic income is not a replacement for healthcare, the health spending cost reduction under such scheme is an interesting topic. A country could probably save a lot on psychiatric hospitals. It's not rare that a person attempts suicide (or looks like they're going to attempt it) because they're poor and in debt, barely holding to a low-paying job; they get put on an observation (during which they'll probably lose their job), stuffed with medication and then thrown back to society at large. The hospitalization itself can cost more than the debt the patient has is worth.
I think such cases are making benefits of BI hard to estimate - because it could eliminate some percentage of costs across so many different aspects of public spending that it's getting hard to keep track of them all.
Basic income is not going to prevent people from taking on unsustainable debts.
Arguably it's less likely to do so than a conventional bureaucratic, means-tested system, since (i) such systems usually directly subsidise things people tend to get into debt for (housing, education/training, and medical care) and have a more flexible, living-costs-related approach to the size of the subsidies on offer and (ii) predatory lenders can chase the indebted far more aggressively when armed with the knowledge their target has a cash income of at least $xx per month and therefore could easily make the payments if they stopped paying for their house, food and health insurance...
