The IT field is a prefect example of the over-educated, need to retrain folks. once you leave the wire guys behind and enter the software side you find turnover is pretty high, even at the best of times. those gaining a bit of experience do look for the next step up and quite often that is in another company. many companies would prefer an 'over educated' employee who can work to their max potential far quicker than an under educated employee who has to be taught both the system and the peculiar protocols of the company.
What many mediocre middle of the pack rats have never seen, mostly because they are so replaceable, is an employment contract for a set wage and period of time. gains both parties peace of mind. I'd say it costs far more to train a high school graduate to be a grunt for Uncle Sam than a Master's Degree applicant for most any job requiring a 4 year college degree.
If a mediocre middle of the pack rat ever looked about they would see millions of people with massive experience and education doing work at a pay grade or two below what they could get in a perfect world. Their 'over education' was no hindrance, they just preferred to stay with a certain company, location, or moved to a new location as part of the spousal equiv, advancing in their career.
it used to be the 'American way'- be all you can be, but it seems equally American to stay in the herd as a middle of the pack rat and scoff at anyone striving to do more than stay with the herd.