the fact that until you find a job that exceeds that you get no benefit
This is not true, or shouldn't be and doesn't need to be true.
Let's say we set the basic income to 50% the mean wage (which would be about $25k/year basic income, or a little over $2k/mo), and fund it by a 50% tax on all incomes (which is more than offset by the basic income for about 75% of the populace who currently fall below that mean income). A homeless with no income thus suddenly has a free income of about $2k/mo. But every nominal dollar they earn on top of that, they still get to keep 50 cents of it. If they get a full time minimum wage job, that amounts to over $600/mo extra. If they get a full time median-wage job (around $25k), that amounts to around $1000/mo extra. On top of the basic income. By the time they're working a full-time mean-wage job (around $50k), they're making twice as much as the basic income, after basic income and the taxes they pay to fund it are factored in (and the basic income and the taxes they pay to fund it exactly cancel out in that case). And even at that point, there is still motive to continue working; if they make twice that again, they're still going to end up with yet another extra $1000/mo or so (compared to the mean income) after taxes and basic income are accounted for.
If you were to make the basic income something more like $1000/mo, which is barely enough to survive off of in many places (that's slightly more than what my destitute mother's SSI pays), or about 25% the mean income (or half the median income), and fund that with a 25% additional income tax, then instead people would be able to keep 75 cents out of every dollar they earn, on top of their basic income.
In any case, you'd have to set the basic income up in some kind of pants-on-head retarded way (like the way current welfare payments like SSI are set up) in order for it to not pay off to work unless you can get a job paying more than the basic income pays. Any sane way of doing it would provide incentive to work more at any income level. Yes, even the people making a millions per year: if the choice is between doing something that beings in another million of which you get to keep half or three-quarters or whatever, or not doing that and getting nothing at all, which do you think people are going to choose?