A "pure" UBI (that replaces all other welfare programs) redistributes money from the elderly and disabled towards those who are neither.

"This implies that were we to eliminate current income support programs and apply the funds towards a pure UBI, there would be a relative redistribution from low-earners to zero earners, but the first-order effects would be a massive distribution up the earnings distribution, along with a redistribution from the elderly and disabled towards those who are neither, primarily but not exclusively those without children."

empirical