I went through University for 5 years for a Forestry degree. I was interested in forestry and in computer science, but I figured I could teach myself the computer science so I jumped into Forestry.
I don't regret the experience, the parties, the friends, the job I have now because I have that degree, but I definitely regret the heavy debt load I acquired while I was doing it. I wish just one person would have explained the concept of "borrowing from your future" while I was spending those loans.