> That's a more gradual phase-out, but it still is an effective marginal tax rate of 50%+ – a level that wealthy earners would complain about to no end.

Yeah, my wording could have been better. The suggestion that I've seen for UBI is $12k/year (which is clearly not enough to live on in today's economy), with the $2:$1 reduction being only for the UBI, and then standard taxes starting after that.

This system was actually proposed a looong time ago (like 1970s, I think). Just by giving everyone a massive tax credit to start with.