I felt the exact same way (almost exactly 7 years as well!). I stopped my entrepreneurial efforts to get a degree, party, travel, etc. Now that I've left that life behind, I regretted "wasting" all of that time when I could have been making money. I wondered where I would be now. It made me depressed quite honestly.

It took awhile for me to realize that it wasn't a mistake in the same regards as making an accounting error, for example. At the time, it was what I truly wanted. However, I truly believe had I not spent those years away from business, I would have not have grown into the person I am now and be heading down the path of starting my own business. I wouldn't have the social skills, connections, or friends that I rely so heavily on now. For all you know, you could have been regretting not enjoying life more if you didn't go to University.

That's why it's not a mistake; there is no right or wrong way to live life. It was a decision. I believe dismissing it as one big mistake is the easy way out. Whether right or wrong, I believe you can use those years to better yourself and your entrepreneurial efforts if you choose to.