The world has changed since a lot of us started out. I'm glad you getting your diploma! There were still a lot of people who got good jobs without one when I graduated high school, but now it is very difficult. At least in California, you cannot be admitted to a union without one. The Iron Workers Local require a diploma *and* a GED. A diploma might not open a lot of doors, but it will keep a lot of doors from being slammed in your face.
Me, I was college bound from early on. I went on to major in anthropology, and completed all the course work for a masters degree. I took another BA in English, and almost finished my coursework for masters in English. Then the need to make a living intervened. I taught English as a second language on and off for about 10 years, and worked in a number of social programs. Funding for these jobs went in the bucket, and I moved to carpentry, especially reproductions for Victorian and Craftsman architectural details, including doors and wooden sash. I did a bit of antique restoration and reproduction.
One thing I learned was that you never know what will become important -- what I considered useless in my studies has too often proved the most useful and practical. I really liked geometry, but didn't see any practical advantage. I have come to understand why really old carpentry books are mostly geometry. I was essential to what I have come to do. Another "useless" course was linguistics. I couldn't have taught English as I have without linguistics studies, and I ended up taking a couple more courses.
Seems like we never know what we need or what will be important until we need it.