Knowledge retention is the wrong metric in a world where you can look anything up in 5 seconds on your phone.

Getting a college degree requires one to work with large amounts of information. Even if you retain none of those facts and figures later in life, you can still retain facility at working with information. And that is much more important to long-term success than how much you memorize.

But a college degree is suppose to be far more than learning how to study and some minor industry exposure which is the vast majority of what it is being used for. It means people are paying for 90% fluff they don't want or need at exorbitant rates to overcome an invisible wall. Numerous classes I myself took and needed credit for to work towards a degree, while entertaining and informative, ultimately ended up as no more than what I could of obtained by reading a decent book on the subject myself. And it cost me a damn pretty penny.

While I think those types of classes should still exist, they shouldn't be used as an artificial financial and time barrier to getting a decent job.

I still retain and use college knowledge in fields not directly related to my programs of study...

You are an outlier, as is just about everybody else commenting here.

I'm a programmer with a bachelor degree, majored in CS and minored in math. I can't do my kids AP calc anymore. I haven't used it in 20 years of programming.