They are like those college aged kids I would see at the Lyndon Larouche table on Seattle city sidewalks for decades. They were always young because as they aged, they grew up and wised up and had to be replaced by “this year’s freshmen”.
Being a Bernie supporter is often just part of being a tweener- between being a kid and being an adult. Most grow out of it. i.e. 2016’s Bernie supporters are older and wiser. Many are now democrats or republicans.
My oldest daughter was an undergrad in 2016. She mostly has a good head on her shoulders. Was in the National Guard, attends church, very practical and responsible. But she did have a focus on student loans and she liked Bernie in 2016.
She now has a graduate degree, is in the working world and is engaged to an active duty Army Major. She’s voting Trump this time around. I figured she get there before too long.