You're going to have to put up some kind of evidence for that. The millenials are used to having nothing, which is what their parents (and their parents' parents) left them.
Okay let me offer you some evidence then. Picture the tent cities and bread lines of the early 1930's. These kept the economically displaced persons during the depression alive. For that matter imagine the tenements of the 1910s and 1920s. If for example in modern American someone proposed that we could save a bunch of money by replacing public housing with something a lot more like those tenements and we should just get rid of SNAP and replace it with bread and soup lines they would be branded as in humane.
If you won't accept it would politically impossible to impose that level of austerity on today's welfare recipients consider many places its already legally impossible, you are not allowed to create a residential unit without at least one toilet. So a shared bathroom for an entire building won't even fly legally in much of this country.
This was a perfectly acceptable standard of living at that time, today people would riot. Heck in the EU the refuges are burning down their free housing because they don't like the assortment of candy available, http://www.dailymail.co.uk/new... .
People on UBI will look at the nicer things the earners have, they won't be able to get jobs because they won't have any skills they can offer that automation isn't meeting. They will either let their jealousy drive them to despair or they will develop a sense of entitlement and decide they should have those nice things too! Its human nature.
Now lets talk about your millenials who are used to having nothing. They are not used to having nothing. They are used to attending universities that look like amusement parks compared to fifty years ago. They are used to paying for this with unsecured loans, which they than ask (and when polled indicate they anticipate) forgiveness for. That is not having nothing, that is having it all and not working for it. Once the graduate they move back home and continue their comfortable if freedom lacking existence.