I do support UBI because it will probably prevent some number of deaths of despair, but capitalists will never let UBI happen for this reason. The reserve army of labor must be trimmed and maintained to prevent a worker uprising, which is the primary function of the opioid crisis.
Greed, seemingly fundamental human nature, causes corruption and suffering. I don't think we've yet developed a society or tool that is immune from such issues, though competition among providers does seem to help.
Hasn't productivity been on the rise the past X years? Shouldn't we have a little slack by this point?
That being said, there are also claimed and real second-order effects of policies whose first-order economic effect is deadweight-loss. The entirety of government fits this description! To use the most trite and least controversial example, confiscating resources to build roads is redistribution from heavier taxpayers to heavier road users (incl downstream beneficiaries), but the second-order effects of a functional transportation are enough that we don't consider it to "make the country as a whole poorer"