I was actually shocked when I found out I wasn't middle class. I knew that I struggled but I didn't know I was considered 'poor' by American standards. I think it is mainly how you spend and save your money. I think for me someone with my level of income is blowing it on the latest iDevice, large screen TVs, and cars that are less than 6 years old. So I think some people THINK they're poor because they aren't responsible with money where someone who makes less than them can even live in their same neighborhood and live quite well.
So yeah, if some millenials think they're poor they just need to look at what they're spending their money on. Unless you literally live on the street sleeping on benches you really can't say you haven't experienced prosperity.
RE: Alexandria Ocasio-Cortez: The new political trend to rewrite your childhood