They opt out of their 401k because they want the extra cash to have McDonalds or taco bell driven and delivered to their apartment via grubhub spending @25 for a burger they could have cooked themselves for $2. They drink only craft beer at $8 a glass as well. I think it's plain old economic ignorance.
My son, who is a corporate tax accountant, got underwater in his mortgage, had a handful of credit cards with balances and couldn’t figure out how get out of his financial hole. And he is a CPA! But I got his head right, and now he’s using good old obsessive-compulsion to stay ahead of the game.
and to be part of the “in crowd”!