going back to college at 21, graduating at 25-27?

It's fine bro. As long as you have the motivation and will, go for it. Doctors study all their lives. No big deal.

Lots of people older than you go back to school to get degrees. Some people have to change professions when they find themselves out of a job in an industry that's shrinking or disappearing. Some people have to work whatever job they can get until their kids are independent and out of the house, allowing them to pursue a degree doing something they enjoy for once. Many people get out of the military without any relevant skills or education in the career they want to pursue at that point. Working for a couple years probably didn't do you any harm, and it probably helped you by giving you a taste of the real world, as well as some time to think about your career. Students who return to school after a substantial break are classified as Reentry Students. In general, reentry students have higher GPAs, lower dropout rates, and higher graduation rates than students who enter college as freshmen. I was a reentry student and I graduated at the top of my class in large public universities for 2 bachelors degrees and a masters degree. I was often the oldest student in my classes, but not always. I didn't seem to have much problem with working with the younger students. The best students would usually try to be in my study groups since I always got A's, and that's a pretty good incentive. I never got a project grade lower than an A because I would ensure that all the work met the requirements and was free of any major errors, even if some students didn't do their part (their grade would get hammered if they flaked out).