The devil doesn't need volunteer advocates, he can afford plenty paid. But you actually make the case for UBI as a replacement for means-tested welfare and its associated cliffs: “the longer you stay away from gainful employment, the more marketable skills you lose.”
That's one of the main points of UBI as a replacement for means-tested welfare [0]: eliminating the perverse incentives against maximizing outside work and for expending energy into working the system that exists with means-tested welfare that has complex eligibility rules and is rapidly cut with outside income. By making the clawback much slower and starting much higher up the income scale through the tax system, UBI, compared to the status quo, rewards gaining additional income in the labor (or other) market and learning skills other than navigating a welfare system.
There is a reason that UBI—under the name “negative income tax” because of the political valence of taxation on that corner of the political universe—was originally a right-libertarian proposal.
> I'm OK with people not working if they don't want to, too, as long as those people are OK with subsistence-level living standards
There's no plausible way a UBI provides anything substantially better than that any time in the near (likely, the lifespan of abyone now living) future, so that shouldn't be a problem.
[0] Perhaps even stronger if UBI is also seen as a (partial or full) replacement for the minimum wage, which could be justified because, unlike means-trsted welfare, it doesn't tail off with income and provides a basic support level for all—there is then no reason that employment must also serve that minimal support purpose, which makes it possible to offer employment whose marginal value to the employer is less than would minimally support an employee, but which would still be positive (and in some cases still have more long-term value to the employee because of experience that could contribute to more valuable future employment.)
That's one of the main points of UBI as a replacement for means-tested welfare [0]: eliminating the perverse incentives against maximizing outside work and for expending energy into working the system that exists with means-tested welfare that has complex eligibility rules and is rapidly cut with outside income. By making the clawback much slower and starting much higher up the income scale through the tax system, UBI, compared to the status quo, rewards gaining additional income in the labor (or other) market and learning skills other than navigating a welfare system.
There is a reason that UBI—under the name “negative income tax” because of the political valence of taxation on that corner of the political universe—was originally a right-libertarian proposal.
> I'm OK with people not working if they don't want to, too, as long as those people are OK with subsistence-level living standards
There's no plausible way a UBI provides anything substantially better than that any time in the near (likely, the lifespan of abyone now living) future, so that shouldn't be a problem.
[0] Perhaps even stronger if UBI is also seen as a (partial or full) replacement for the minimum wage, which could be justified because, unlike means-trsted welfare, it doesn't tail off with income and provides a basic support level for all—there is then no reason that employment must also serve that minimal support purpose, which makes it possible to offer employment whose marginal value to the employer is less than would minimally support an employee, but which would still be positive (and in some cases still have more long-term value to the employee because of experience that could contribute to more valuable future employment.)