Actually anecdotes are evidence. They don't prove correlation or causation in themselves but they are evidence. Also none of your "extensively researched" evidence proves causation. At best you can point to correlation. What I'm saying is that hard work and intelligent choices have far more of an effect on your life than "a degree". Unfortunately those types of things aren't easily compilable. Universities are selling a solution to a self created and self perpetuating problem. When everyone has a masters the answer will be to get a phd and when everyone has a phd a new degree with be made. In 100 years you can expect baskin robins university with 31 degrees. I don't doubt that education is valuable but you can get it much cheaper than by going to university.
Would you be skeptical of "research" from the cigarette manufacturers that said tobacco is good for you and that tailor mades are the best way to get it? Color me unconvinced that more schooling is the answer.
It could well be that a degree is the best way to spend a half million dollars but I don't think it is.