18-22 year olds are voting in their first primary and think things will always be the way they are now.
In six months when nobody gives two sh*ts about Bernie, the media has 24/7 wall-to-wall Hillary coverage and all their liberal friends are saying the world depends on people voting for Hillary against the DISGUSTING racist, sexist, homophobic, immigrant-hating, poor-hating, corrupt wall street hack [insert GOP candidate here], a declaration that they're standing strong for Bernie and won't vote for Clinton will just draw mocking laughter.
They'll vote for Clinton. In droves.
This.
Not to mention the likes of Bernie and Warren will be certainly aggressively campaigning for Clinton come the GE.