Look at the tax reform debate now: When they proposed taking away deductibility of mortgage interest or state and local taxes deductions, I started seeing headlines from the New York Times and Washington Post about how this a “Middle Class Tax Hike”...
I would compare UBI to the "second system syndrome" with software developers: If only we can start over with an entirely new platform rather than addressing the technical debt in the current system, all would be well.
Every single proposal of UBI has included it replacing all other welfare benefits
Only so that their cost calculations don't go crazy and seem sustainable. No one in the UBI side is even remotely interested in deleting previous welfareI think you're working from some wrong assumption who these UBI proponents are, and what their motivation is. Just to give you an idea, Wikipedia lists Elon Musk, Tim Berners-Lee, Mark Zuckerberg, Sam Altman, Bill Gross, and Tim Draper, among others. These aren't lazy know-nothings trying to get you to finance their lazy Tuesdays.
I don't have any issue with billionaires believing into UBI and sending cash to Kenyans. I don't know their true agenda, but they might gain some political influence / power when they'll try to implement this into western countries (and it will be with our money this time of course, not theirs).