This is a well-known opinion from Mr Musk, and the story has been submitted many times, some with significant discussion. In case you're interested in what HN "thinks" it might be worth reading some of them. Of course, these are quite old now, so if you have anything to add you'll have to do it here.
https://news.ycombinator.com/item?id=12884477 (31 comments)
https://news.ycombinator.com/item?id=13150173 (16 comments)
https://news.ycombinator.com/item?id=13139261 (11 comments)
https://news.ycombinator.com/item?id=12890376 (5 comments)
https://news.ycombinator.com/item?id=13674967 (1 comment)
https://news.ycombinator.com/item?id=13644567 (1 comment)
Other submissions don't have any comments:
https://news.ycombinator.com/item?id=13678268
https://news.ycombinator.com/item?id=13677450
Mick Resnick's "Feelies" is based around future society where this has happened.
This is scary as fuck when you think about it. Why? Because the idea of a UBI basically pre-supposes some sort of entity that does something like collecting taxes and then taking responsibility for divvying things up to provide the basic income. Call it "government" or what you will. Then look at how corrupt our government is now. Now think about what happens when your very survival depends on that government divvying up the spoils and doing the right thing.
Do the math. Corruption will become far more pronounced than it is now and most of us will be forced to survive on $2 / day, while the elites live larger than ever. You think income inequality is a problem now? It'll only get worse once (and if) technological unemployment puts all (or most) humans out of work.
A world where you can't sustain yourself by creating value through some independent initiative / effort is probably going to be a very ugly world.