On paper, UBI could potentially solve all these issues and create a better society where everyone has funds to fall back to, which would give them a structure to build on, but is it sustainable as a long term solution? I do not think so.
The funds to support such a scheme has to come from somewhere and the likely source is the coffers of tax payers. Most would not agree with increases in taxes.
UBI is a great idea, but is often misunderstood. It's simply not true that new money has to come from somewhere, or that everyone's taxes will go up.
There is no need for new money to fund a UBI, it is self-funding. It can be considered (simplistically) as being similar to a modification of tax bandings.
If you are an average earner, then under UBI you would expect to receive around the same total amount of money each month. You'd get your guaranteed minimum UBI from the state, which of course forms part of your income.
Some sample figures* to illustrate the point:
You earn $3k per month under the current system. You get your first $1k per month tax-free, then pay 20% on the next $1k, then 40% on the next $1k... so you get $3k, and pay (1000*.20 + 1000*.40) = $600 tax, so keep $2400 after tax.
Under UBI, you get a guaranteed UBI of $1k per month. You still earn $3k per month, so you now receive $4k in total before tax. You still get your first $1k tax-free (the UBI), your next $1k is taxed at 40%, your next $1k at 50%, your next $1k at 60%... you pay (1000*0.40 + 1000*0.50 + 1000*0.60) = $1500 tax, so get to keep $4000 - $1500 = $2500 after tax.
Your income has increased slightly, because everyone gets a UBI, so the state no longer has to use your taxes to fund the welfare system.
You will also note that someone on an ultra-low income of $1k per month kept $1k under the current system, but ($2k - $1k*0.40) = $1.6k under the UBI system, and is much better off.
Obviously a bit of a simplification, but that's the basics of how it would work.
*
Please don't try to argue that $3k is less/more than average income. I chose this amount simply because it is easier to demonstrate the principle.