They wont, new kids grow up every year and they hear mixed messages, some says college is a scam while others says it is the golden ticket. They have to make a decision, so lots trusts (or just hopes for) the golden ticket.
This will continue as long as colleges are allowed to market themselves as golden tickets.
My previous job I worked at required a Bachelors in business of any kind. I got it because I worked at the company and basically beat out external candidates even though I didn't have a degree. Know what it paid?
$15/hr.
This is why people are duped into college degrees.
The contractors I talk to are booked out for weeks, and I need their expertise much more than they need my business. I'm not convinced that lacking a degree shuts people out of good jobs. My cynical take is that there's a mismatch between what people are willing and able to do, and what activities are valuable.
Most people aren't willing to work inside peoples' mouths all day. Dentists make bank. The HN crowd notwithstanding, most people would hate carefully crafting digital products all day. Software devs make bank. Most people aren't willing to crawl underneath houses to hook up potentially-dangerous electric/gas lines. etc.
In a past life, I tried the general laborer gamit and it's impossible to get a job there too. Simply cause nobody hires you unless it's by word of mouth. So it's even worse than being shut out for not having a degree. So overall, it's no so much that people don't believe that they need a degree, it's the path of least resistance since you can at least get your foot in the door through a company once you pass the minimum qualifications. General labor stuff, good luck getting a job in a specialized field. I tried breaking into HVAC and I couldn't even get an unpaid apprenticeship cause people just won't do it.
The thing is, most kids go to school not knowing what they want to do. If that is the case, going to college is the absolute worst possible decision you could ever make. On top of that, you might even be going into a field you despise but can't back out now.