I doubt that's the intrinsic value of the degree (a la supply and demand), but rather the mindset, social-economic status, and background of someone that goes to college. (At least in the US)
Exactly this, the degree is used as a proxy for the actual qualities that employers for certain higher paying positions are screening for. But that's not what they tell you. They tell you that 'having a degree will get you a high paying job'. This stops being the case if the everyone has a degree and the proxy relationship no longer works. The honest thing to say is have the correct "mindset, social-economic status, and background" and you will get a high paying job.
