The Old Millennial vs. the Young Millennial

Jesse Singal, writing in NY Mag, argues that there is a difference between "old millennials" and "young millennials".

As someone who graduated directly into Thatcher's Britain and consequentially can't stand to be labeled a "Baby Boomer", I feel for him or her.

They argue that there's a split that occurred due to the introduction of the iPhone (2007) and the Great Recession (2008) that caused a major difference in young people's outlooks.  I can believe that; it seems more likely that cell-phone availability and job insecurity is a much likelier contributor to cautious vs. risk-taking personality than the arbitrary Arabic numeral group giving your birth cohort.