I'm assuming you graduated with a bachelors? At the end of your BS, it's definitely worth thinking about opportunity cost (eg. is graduate school "worth it"). When I was working toward my PhD (engineering, with goals to eventually be entrepreneur)... I had to fend off detractors: "if you want to make money or do a startup, stop at a MS and get out there." I politely disagreed. Getting my PhD was a personal goal and shouldn't detract from future entrepreneurial activities.
Like you, I lived frugally during my entire educational experience, and the tuition was largely paid for through scholarship / fellowship. For talented people (who could prosper after dropping out), college expenses can be fairly minimal.
So where are those types of values in the calculations?
Now that I've graduated my starting job is ~$60k with a $20k annual raise once I've been in this position for a little over three years. There's not one friend that started work directly out of school that I can say that for.
Not to mention my degree allows me to venture to the upper ends of this company where education is a requirement while they'll plateau in seniority because of that.
Again, way too many variables and gray areas for us to do a number to number comparison because no two situations are identical and the idea of "average" or "typical" probably only makes up a small percentage of personae anyway.