There are three main reasons for this. One is that wages have stagnated for most jobs since the 1980s. Which has meant that it's harder to get ahead and easier

There are three main reasons for this. One is that wages have stagnated for most jobs since the 1980s. Which has meant that it's harder to get ahead and easier to fall behind unless you step into a high paying career early or are lucky enough to climb some business ladder into high ranks. Another is that if you look at the employment after the 2008 economic crash the majority of the impact was on folks under 25. Unemployment shot up, as did underemployment, and that situation has persisted for the better part of a decade before recovering at an agonizingly slow pace. Literally millions of people, most of them millenials, just fell out of the job market, and millions more were stuck in crappy, underpaying jobs for years. That kind of thing has a dramatic long term impact on your career development and thus your earnings, your savings, your personal investment, and so on. The last is the massive cost increases in housing and education. In combination with the other two these things have significantly hampered millenials ability to earn money, to save money, and to build up wealth and stability via home ownership (which has traditionally been a classic way to do so for Americans). Millenials can barely afford to live in the cities where there are jobs and if they don't have a decent-ish job they can't afford to move to where there are, they can't save, and they can't accrue wealth.