Because wanting income as you put it, without producing value, has never worked very well. This is why capitalism has pulled billions out of poverty and communism (or all the other pie in the sky give me free stuff detached from what I trade back) hasn't.

Income is a proxy for you to trade value you create to another that is willing to trade back.

So yeah, go ahead and try whatever you think mankind has not invented despite thousands of years and billions of people wanting to have stuff without trading for it. Most such schemes end up hurting people far more than any help.

>the majority of the human race

... who has gotten incredibly richer than at any time in history and for more people than ever.

Agreed. Universal basic income and capitalism can coexist. If everyone was given an annual stipend suitable for a healthy life, motivated people could still choose to increase their personal wealth by working. The surplus wouldn't need to be owned by the state, like it is under communism.

I know that even if I was given $20k a year by default, I'd still work in order to make more.

Yeah. 'Real' communism hasn't been tried! /s

Everyone here knows the last time it was tried, it ended in complete failure. Just like the previous attempts did. Such hopelessly utopian ideas getting laughed out of the room once again.

What, concretely, do you propose then?