This is precisely one of the problems with means-tested benefit programs, especially with an uncoordinated collection of such programs, that UBI, with its unconditional nature, is designed to solve. I don't see how that description of the effect of Section 8 vouchers (even if it is assumed to be both accurate, and generalizable) illustrates that UBI is a "retarded ivory tower idea".
There's a degree to which this is true, but there is a radical difference between tax system "means testing" and that with existing means-tested public benefit programs. With existing poverty support programs, its quite possible to lose nearly (and in some cases even more than) $1 in public benefits for each $1 in outside income (and much more at certain breakpoints), and to do so while your total income is under the federal poverty level.
OTOH with stae and federal income and payroll taxes together, you can -- in a relatively high income tax state like California -- currently reach a maximum marginal rate (including the employer share of medicare taxes, and assuming that payroll taxable income and income taxable income are equal, which both overstates the tax rate on nominal income and ignores minor differences between the income those two taxes apply to) of 55.8%, but it takes $1 million in taxable income to reach that point (some UBI proposals would add higher maximum marginal rates, at even higher income levels.)
So, sure, the tax system reduces the incentive for earning additional income, especially at higher income levels; the problem UBI address is that existing poverty support programs do much more to reduce the benefit for earning additional -- or even any non-benefit -- income, and they do it at poverty levels.
(And, on top of that, they add -- with each program -- additional layers of bureaucracy to enforce those rules, rather than letting the tax system be the single point in which means are considered.)
If you grow up surrounded by people who subsist on poverty-wage welfare checks and you are literally isolated to that community because you parents are a part of it, how in the universe are you ever meant to obtain aspiration or escape it? There is no special snowflake effect here, people are the product of their circumstances (another important sociological observation the last two decades of post-cold-war-propaganda has presented ample evidence towards) and if you have a society built on a foundation of traditional racism and segregate people on that basis you should not be surprised when the members of that group lack strong work ethic or an attitude of improvement. They are put in a cultural cell with iron bars on the windows and while you can with effort escape it you are in a prison with all your friends, family, and everyone you have ever met, so when even given the option to escape, you often do not. It is why prison recidivism is so high with long-term incarcerated, and why particularly ostracized minority groups show less economic mobility.
When there is no hope, there is no plan esp. long term plan, life becomes day to day exercise of attaining happiness now!!!