[orangecat]

If I have saved maybe a million in cash, UBI would encourage me to just stop working.

You'd already be "encouraged" to take a lower-paying part time and/or less stressful job. But most millionaires aren't going to be satisfied with the downgraded lifestyle that would entail.

doesn't do much for the poor

It does a lot for the poor. It lets them earn additional money without worrying about losing benefits, which is a big problem with current welfare systems. And more importantly it gives them negotiating power; they can walk away from abusive employers without the worry of homelessness or hunger.